Genus Pleuromeris Conrad 1867 



Pleuromeris tridentata (Say 1827).* Three-toothed cardita. Fig- 

 ure 91. 



The three-toothed cardita is distributed from North Caroli- 

 na to all of Florida and into the Gulf of Mexico (Johnson 1934; 

 Morris 1973: Abbott 1974). 



Pleuromeris tridentata is represented in the NEFC Speci- 

 men Reference Collection by 168 specimens from 61 samples 

 (Table 5). 



Our samples are from the continental shelf between Cape 

 Hatteras, N.C., and the Florida Keys (Fig. 91; Theroux and 

 Wigley footnote 4. table 157). 



Pleuromeris tridentata is commonly found in moderately 

 shallow to moderately deep water which ranges from 0.3 to 

 227 m (Johnson 1934; Porter 1974). 



Our samples are from depths which range between 9 and 

 233 m with a mean of 33 m. The bulk of our samples are in the 

 0-24 m and 25-49 m depth range groupings which contain 43 

 and 32% of the samples and specimens, respectively, in the 

 former and 44 and 56% of the samples and specimens in the 

 latter: 10% each of samples and specimens are in the 50-99 m 

 grouping while 2 and 1%. respectively, are in the 100-199 m 

 and 200-499 m depth range groupings (Table 172). 



Samples containing the three-toothed cardita were 

 obtained from gravel, shell, sand-shell, sand, and silty sand 

 substrates. Sand sediments contained the greatest amount of 

 both samples and specimens which was 48 and 669c. respec- 

 tively, while sand-shell was next with 419c of the samples and 

 23% of the specimens. Significantly lower amounts occurred 

 in the other sediment types (Table 173). 



Genus Pteromeris Conrad 1862 



Pteromeris perplana (Conrad 1841a). Flattened cardita. Figure 

 96. 



This species occurs from North Carolina to Florida and is 

 also found in the Gulf of Mexico (Morris 1973; Abbott 1974; 

 Porter 1974). 



Pteromeris perplana is a common bivalve represented in 

 our collection by 28 specimens from 14 samples (Table 5). 



Our samples are from the continental shelf between Cape 

 Fear, N.C.. and slightly north of Miami, Fla. (Fig. 96; Ther- 

 oux and Wigley footnote 4. table 169). 



Depths in which this species is found range between 2 and 

 116 m of water (Abbott 1974: Porter 1974). 



Our samples are from water depths which range between 10 

 and 43 m with a mean of 30 m. The majority of both samples 

 and specimens are in the 25-49 m depth range grouping which 

 contains 799c of the samples and 899c of the specimens: the 

 0-24 m grouping contains 2 1 9c of the samples and 1 1% of the 

 specimens (Table 174). 



The flattened cardita samples were obtained from four 

 sediment types: sand-gravel contained 79c of the samples and 

 4% of the specimens: shell contained 149c of the samples and 

 7% of the specimens: sand-shell contained 2 19c of the samples 



'Abbot (1974) has '•{Say. 1826)" for this species, it should be (Say 1827), see 

 under References. 



and 36% of the specimens; and sand contained 57% of the 

 samples and 54% of the specimens (Table 175). 



Family ASTARTIDAE 

 Genus Astarte Sowerby 1816 



Astarte borealis (Schumacher 1817). Boreal astarte. Figure 10. 



This species is reported to occur from Arctic seas and 

 Greenland to Massachusetts in the North Atlantic, and from 

 Alaska to Japan in the North Pacific (Johnson 1934; Clarke 

 1962; Tebble 1966; Morris 1973; Abbott 1974; Emerson et al. 

 1976). Ockelmann's (1958) records for Arctic regions are 

 quite extensive showing the boreal astarte occurring at East 

 and West Greenland, Jan Mayen, Spitzbergen. Franz Joseph 

 Land, Novaya Zemblya, the White Sea, along the Murman 

 Coast, Finmark, in the Barents, Kara, and Siberian Ice Seas, 

 in the Bering Sea and Strait in Alaska, the seas north of 

 America, Grinnell Land. Baffinland, the Parry Islands, Hud- 

 son Strait. Labrador, Newfoundland, Nova Scotia, Iceland, 

 Massachusetts Bay, off Norway south to Bergen, in the 

 northern part of the North Sea, the Kattygat, Danish Belts, 

 the Sounds in the Baltic to east of Bornholm. In the Pacific it 

 extends southward from the Sea of Okhotsk to the Aleutians, 

 Japan, and Forrester Island. 



The boreal astarte, a common bivalve of North Atlantic 

 waters, is represented in our collection by 22 specimens from 

 18 samples (Table 5). 



The majority of our samples are from the continental shelf 

 and adjacent banks south of Nova Scotia. Several samples 

 occur on the Northeast Peak of Georges Bank and three 

 samples on the southern New England continental shelf (Fig. 

 10; Theroux and Wigley footnote 4. table 16). 



The main distribution of this species is panarctic and cir- 

 cumpolar with Boreal outposts (Ockelmann 1958); Dance 

 (1974) placed it in the Arctic. Boreal, Aleutian, and Trans- 

 atlantic provinces. 



The boreal astarte is found at depths ranging from to over 

 2,500 m (Ockelmann 1958; Clarke 1962). 



The depth range of our samples is 30 to 95 m with a mean of 

 74 m. Eighty-nine percent of our samples and 91% of our 

 specimens are in the 50-99 m depth range grouping, the re- 

 mainder are in the 25-49 m grouping (Table 176). 



Astarte borealis appears to prefer coarse grained sedi- 

 ments. Thirty-five percent of our samples occurred in each of 

 two sediment types: gravel and sand-gravel, while 24 and 6%, 

 respectively, occurred in sand and sand-shell sediments. In 

 terms of specimen density, 43% occurred in sand-gravel, 29% 

 in gravel, 24% in sand, and 5% in sand-shell (Table 177). One 

 sample with one specimen was unclassified with regard to 

 sediment type. 



Astarte castanea (Say 1822). Smooth astarte. Figure 11. 



The smooth astarte is distributed from Arctic seas to Cape 

 Hatteras, N.C. (Johnson 1934; Morris 1951, 1973; LaRocque 

 1953; Ockelmann 1958; Abbott 1968, 1974; Emerson et al. 

 1976). 



Our samples are from the continental shelf ranging from the 

 Northeast Peak of Georges Bank to slightly north of the 

 mouth of Chesapeake Bay off Maryland; a small group of 

 samples on the Scotian Shelf and at the mouth of the Bay of 



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