Chlamys bartschi (Arnold, 1906)
ARNOLD, R. 1906. The Tertiary and Quaternary pectens
of California. United States Geological Survey Professional Paper, 47: 1-264,
pls. 1-53. [p. 107, pl. 41, fig. 3]
1906 Pecten (Chlamys) bartschi Arnold, 1906
R. Arnold, 1906, plate 41.
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«Description.— Adult shell averaging about 60 millimeters in altitude, somewhat shorter than high, convex, slightly inequilateral; base regularly rounded; margins smooth. Valves with about 40 prominent (more or less unequal) narrow threadlike ribs, ornamented on top by numerous short imbricating spines; interspaces deep, narrow, and channeled; lateral areas rather narrow, perpendicular to disk, and slightly concave. Ears similar to those of P. islandicus.
Dimensions.— Alt 62 mm.; lat. 50 mm.; diameter 28 mm. This species, of which only two or three rather poorly preserved specimens are known, is quite closely related to P. opuntia, but is readily distinguishable by its much larger size when adult, lack of concentric constriction in the later stages of growth, and relatively shorter disk. P. bartschi is found in beds of probable lower Pliocene age at Crescent City, Cal., where it is associated with Terebratalia near hemphilli Dall, Phacoides acutilineatus Conrad, and Pecten parmeleei Dall. The type is figured and is now in the U. S. National Museum, No. 164841. RANGE.
Pliocene (lower). Crescent City, Del Norte County, Cal., south side of Light-House Point, north of wharf (Diller).»
RALPH ARNOLD, 1906
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«There is great uncertainty about this species and its possible synonyms. Arnold's type is so poor that practically nothing can be done with it. The ribs and spines are coarser than those of opuntia, and it is unlikely that it is closely related to opuntia. The type of sancti-ludovici is so like hastatus that it should perhaps be included with that species as a variety. On the other hand, there are specimens from the upper Miocene of San Luis Obispo Co. in the collection at Stanford University that are practically indistinguishable from some living specimens of P. varius (Linnaeus) from Europe. These Stanford Miocene specimens have more numerous, simpler ribs than the type of sancti-ludovici. A small one, like the young of varius, shows the characters of egregius. The type of hodgei is like sancti-ludovici except that each of the primary ribs splits near the apex, thus making the number of ribs more like that of typical bartschi. Hertlein compares his species to P. halimensis Makiyama¹ from the Pliocene of Japan.
Typical bartschi is a large form on which the intercalaries are well developed, making the ribbing quite complex. It is possible that the other forms should be separated as varieties, or even that bartschi should be referred to islandicus. The paratypes of hodgei have more numerous, finer ribs and are more like P. tenuigranosus Reeve from the west coast of Panama (Conch. Icon., Vol. 8, Pecten, pl. 35, species 176, 1853).» ¹ Pecten halimensis Makiyama, Japanese Jour. Geol. Geog., Vol. 2. p. 23, pl. 4, fig. 1, 1923.
GRANT, U. S. IV & H. R. GALE. 1931. Catalogue of the marine Pliocene and Pleistocene Mollusca of California and adjacent regions. Memoirs of the San Diego Society of Natural History, Volume 1, 1036 p., pls. 1-32, 15 text figs. [p. 168]
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