Parvamussium alaskense (Dall, 1871)
DALL, W. H. 1871. Descriptions of sixty new forms of mollusks from the Westcoast of North America and the North Pacific Ocean, with notes on others already described. American Journal of Conchology [New Series], 7: 93-160, pls. 13-16 [p. 155, pl. 16, figs. 4a, 4b]
1871 Pecten (Pseudamussium?) alaskensis Dall, 1871
1906 Pecten (Propeamusium) [sic] riversi Arnold, 1906
1916 Pecten (Propeamusium) [sic] levis Moody, 1916
1924 Pecten calamitus Hanna, 1924
1926 Pecten intuscostatus var. multicostata Yokoyama, 1926
1931 Pseudamussium simanense Kuroda, 1931
1931 Pecten intuscostatus var. sawanensis Hertlein, 1931
1906 Pecten (Propeamusium) [sic] riversi Arnold, 1906
1916 Pecten (Propeamusium) [sic] levis Moody, 1916
1924 Pecten calamitus Hanna, 1924
1926 Pecten intuscostatus var. multicostata Yokoyama, 1926
1931 Pseudamussium simanense Kuroda, 1931
1931 Pecten intuscostatus var. sawanensis Hertlein, 1931
W. H. Dall, 1871, plate 16.
|
«Shell nearly equilateral, inequivalve, flesh-color with a blush of salmon-color on the umbo of the superior valve. Internally white, the salmon-color showing through the valve. Shell suborbicular, barring the auricles, which are wide and prominent. Lower valve flattened, .1 in. smaller than the upper one; sculpture of fine, close, equal, concentric ridges, sharply defined and separated by narrow non-canaliculated grooves. Valve covered with a fine velvety epidermis, ashy and very finely radiately striate. Surface of the valve, except for the ridges, smooth. Anterior auricle long, prominent, with a deep sinus. Posterior auricle small; both with strong elevated lines of growth, which rise into scales on the eight or nine fine ribs with which the anterior auricle is furnished. Hinge line straight, smooth. Inside of the valve polished, furnished with twenty-one rounded; radiating ribs, with traces cf others intercalated near the margin: nodulous or swollen at the more prominent ridges of growth and at the margin.
Upper valve similar, inside; anterior auricle shorter, not so deeply sinuated. Valve more convex than the under one, and a little larger. Dorsal areas finely granulate. Umbo smooth; half way toward the margin the striae of increase become more conspicuous, and about thirty-five pseudo-ribs radiate toward the margin. These are formed by the elevation of the concentric lines of growth like ruffles, in such a way that the edge of one fluting of the ruffle overhangs the beginning of the next, and so on. These are very fragile, and when broken away show the nearly smooth surface of the valve underneath, without any true rib at all. Faint grooves are intercalated between the pseudo-ribs toward the margin. Lon. .76, alt. .76, diam. .22 in., width of hinge line .34 in. Angle at the umbones, 100°. Animal with the mantle margin profusely furnished with lemon yellow tentacular filaments, and on the upper side only with six pairs of black ocelli; inner smooth part of the mantle pencilled with dark brown, especially on the inner side. Foot cylindrical, terminating in a minute rounded knob; inner edge furnished with half a dozen small papillae. Body yellowish white, with a pointed sac filled with ova, occupying the greater part of the cavity. Byssus minute; liver greenish, muscles large, consolidated. Habitat, One lower valve, North Harbor, Unga Island, six fathoms mud. Dall, 1865. One larger living specimen, exactly agreeing, Port Etches, Chugach Gulf. Dr. Minor, U. S. Rev. steamer, Wyanda.
This remarkable little species is apparently quite distinct from any described Pecten. It is, at present, impossible for me even to decide in which section of the genus it should be placed.
It differs from the young of tenuicostatus, Mighels, (= Magellanicus, Lam.) in its sculpture and internal ribs and more rounded shape. P. groenlandicus is smooth and otherwise different. The internal ribs differ from those of Pleuronectia in being nodulous, the internal supports of the latter are wanting, and the auricles are notched. The valves close perfectly. Altogether, this is a very interesting species.» WILLIAM HEALEY DALL, 1871
|
«Parvamussium alaskense (Dall, 1871). Alaska glass-scallop.
Pecten (Pseudamussium) alaskensis Dall 1871; Pecten (Propeamusium) riversi R. Arnold 1906; P. (Propeamusium) levis Moody 1916; P. calamitus Hanna 1924; Pecten intuscostatus multicostatus Yokoyama 1926; P. intuscostatus sawanensis Hertlein 1931, nomen novum pro P. intuscostatus multicostatus Yokoyama. Type locality: Port Etches, Chugach Gulf, Alaska. Distribution: Throughout the Bering Sea, from the Pribilof Islands to Bristol Bay, Alaska, south to San Diego, California, and west to the Sea of Okhotsk and northern Japan; 15–1530 m; common.» DRUMM, D. T., K. P. MASLENIKOV, R. V. SYOC, J. W. ORR, R. R. LAUTH, D. E. STEVENSON & T. W. PIETSCH. 2016. An annotated checklist of the marine macroinvertebrates of Alaska. NOAA Professional Paper NMFS, 19: 1-289. [p. 142, 143]
|
«The present species is characterized by having a subcircular shell, medium size, ornamented with radial riblets which are irregular in strength in the left valve, and with fine, close, equal concentric ridges which are sharply defined and separated by narrow grooves in the right valve. Moreover, the inside of the shell is furnished with many radial fIne radiating ribs which are more prominent at the ventral margin.
The present species found living north of the Tsushima Strait in the Japan Sea, and the Bering Sea to Panama Bay usually in deep water (ca. 150-400 m). Reg. No. 6124. Locality and geological horizon: Maruyama, Imagane-machi. Setana formation (coarse-grained sandstone).» KANNO, S. 1962. Molluscan fauna from the so-called Setana Formation, southwestern Hokkaido, Japan. Science Reports of the Tokyo Kyoiku Daigaku [Section C -Geology, Mineralogy and Geography], 8 (73): 49-62, pls. 1-5. [p. 56]
|
Polynemamussium alaskense (Dall), 1871; S. Kanno, 1962, Molluscan fauna from the so-called Setana Formation, southwestern Hokkaido, Japan, plate 4, figures 6, 7.
|
«Pecten simiIis described by Yokoyama from the Pliocene Koshiba formation of Miura Peninsula, Kanagawa Prefecture, and, Propeamussium (Cyclopecten) simanense reported by Kuroda with figure but without description from the sea bottom off Toyama Prefecture are considered to be synonyms of the present species.
Two external casts (PI. 2, Fig. 2) and an internal mould of this well known species from the Kiwada formation in Chiba Prefecture was studied. Their dimensions (in mm)s are as follows.
These specimens are preserved in a mudstone of the upper part of the Kiwada formation. From the lower part of this formation, abundant spocimens of Palliolum peckhami (GABB) and Palliolum aff. randolphi (DALL) have been collected.
Associated with the present fossils are Dentalium rhabdotum (PILSBRY), Dentalium sp., Crenella diaphana (DALL), Nuculana? sp., Yoldia sp., Natica janthostoma (DENSHAYES) and Echinoid 2 spp. From the lower part, Yoldia thraciaeformis (STORER), Yoldia 4 spp., Acila divaricata HINDS, Crenella? diaphana DALL, Periploma sp., Cardiomya sp. and a solitary coral have been reported by K. Sakakura. K. Koike studied the fossils and sediments of this formation and concluded that the age is lower Pliocene, and that the formation was probably deposited on the continental slope or on the margin of the continental shelf where the environment is influenced by warm current streams on the surface and by boreal current below.» ÔMORI, M. 1955. On some fossil new species of the genus Propeamussium from Japan. Science Reports of the Tokyo Kyoiku Daigaku [Section C - Geology, Mineralogy and Geography], 4 (27): 7-22, pls. 1-2, text-fig. 1 [p.18]
|
Polyneamussium alaskensis (Dall); M. Ômori, 1955, On some fossil new species of the genus Propeamussium from Japan, plate 2, figures 2-14.
|