ABSTRACT
The Shattuck Zone 10 bivalve fauna also contains a number of tropical-subtropical genera and species. Some of the more important of these are the ark shell Barbatia marylandica (Conrad, 1840), the bittersweet clam Glycymeris parilis (Conrad, 1843), the file shell Lima papyria Conrad, 1841, the pen shells Atrina harrisi Dall, 1898 and Atrina piscatoria Glenn, 1904, the leafy jewel box Chama chipolana subspecies, and the kitten’s paw Plicatula densata Conrad, 1843. Besides these few tropical species, the bulk of the Shattuck Zone 10 bivalve fauna was dominated by typical Transmarian species such as the ark shell Dallarca subrostrata (Conrad, 1841), the venerids Mercenaria blakei Ward, 1992 (Figure 4.4B), Melosia staminea (Conrad, 1839) (Figure 4.2E), and Dosinia blackwelderi Ward, 1992 (Figure 4.3E), the lucinids Phacoides foremani (Conrad, 1841) (Figure 4.5E) and Stewartia anodonta (Say, 1824), the large corbulid Bicorbula idonea (Conrad, 1833) (Figure 4.5F), the astartids Astarte cuneiformis Conrad, 1840 (Figure 4.3M) and Astarte calvertensis Glenn, 1904, the bizarre, coiled glossid clams Glossus marcoei (Conrad, 1842) Figure 4.2J) and Glossus mazlea (Glenn, 1904) Figure 4.2L), the crassatellid Marvacrassatella melina (Conrad, 1832) (Figure 4.3C), the cockle shells Chesacardium craticuloide (Conrad, 1845)(Figure 4.5B), Chesacardium calvertensium (Glenn, 1904), and Chesacardium leptopleurum (Conrad, 1841), the scallop Chesapecten coccymelus (Dall, 1898), and the geoduck Panopea whitfieldi Dall, 1898. A distinct arctic component was also present in the Shattuck Zone 10 bivalve fauna, including the astartids Astarte cuneiformis Conrad, 1840 (Figure 4.3M), Astarte vicinia Say, 1824, Astarte thomasii Conrad, 1855, and Astarte calvertensis Glenn, 1904 and the cold-water crassatellids Cyclocardia castrana Glenn, 1904 and Cyclocardia calvertensis Petuch and Drolshagen, new species (see Systematic Appendix) (Figure 4.1D).
