Our collections of waved astarte occurred in all sediment 

 types, but most frequently in sand (30% of samples), and till 

 (37% of specimens). They were least frequent in sand-shell, 

 shell, and silt (Table 189). 



Astarte sp. Figure 16. 



The NEFC collection contains 533 specimens from 94 col- 

 lections which are classified as Astarte sp. (Table 5). 



The collections of Astarte, without specific determina- 

 tions, are distributed along the continental shelf to the north 

 of Delaware Bay in a fairly widespread pattern on the South- 

 ern New England shelf, on Georges Bank, and into the Gulf of 

 Maine (Fig. 16; Theroux and Wigley footnote 4, table 25). 



The depth range for our collections is from to 690 m with a 

 mean of 192 m. A fairly consistent pattern of diminishing 

 sample and specimen density persists from the 50-99 m group- 

 ing to the 500-999 m grouping; small quantities occur in the 

 two shallowest groupings (Table 190). 



The largest percentages of samples for this genus were 

 found in sand and silty sand substrates which contained 42% 

 and 17%, respectively; gravel, sand-gravel, till, silt, and clay 

 accounted for from 3 to 13% of the samples. One anomaly 

 with regard to the number of specimens occurred in till sub- 

 strates which contained 16% of the specimens but only 9% of 

 the samples while silty sand areas accounting for 17% of 

 samples yielded 13% of the specimens (Table 191). There are 

 6 samples containing 18 specimens which are unclassified 

 with regard to sediment type. 



Family CRASSATELLIDAE 

 Genus Crassinella Guppy 1874 



Crassinella lunulata (Conrad 1834). Lunate crassinella. Figure 

 30. 



The lunate crassinella is reported to occur from Mas- 

 sachusetts to Florida, and from Texas to Brazil; it has also 

 been reported in the West Indies and Bermuda (Johnson 1934; 

 Abbott 1968, 1974; Emerson et al. 1976). 



Crassinella lunulata is represented in the NEFC collection 

 by 226 specimens from 87 samples (Table 5). 



Our samples are from the southern portion of the study area 

 beginning southeast of the mouth of Chesapeake Bay, on the 

 continental shelf south to Miami, Fla.: however, three sam- 

 ples were obtained in the Vineyard Sound-Nantucket Sound 

 region (Fig. 30; Theroux and Wigley footnote 4. table 47). 



This species inhabits the Virginian zoogeographic province 

 (Coomans 1962). 



The bathymetric distribution of this species ranges from 1 

 to 549 m (Abbott 1968; Porter 1974). Our samples are from 

 depths which range from 7 to 135 m with a mean of 29 m. The 

 amounts of both samples and specimens in our collection 

 diminish with increasing depth range. Forty-nine percent of 

 the samples and 54% of the specimens are in the 0-24 m depth 

 range grouping; 40% and 39% respectively, are in the 25-49 m 

 grouping while 6% of the samples and 4% of the specimens are 

 in the 50-99 m depth range grouping; 5 and 4% of samples and 

 specimens, respectively, are in the 100-199 m grouping (Table 

 192). 



This species is reported to occur on gravelly or shelly 

 bottom (Emerson et al. 1976). 



The majority of our samples were in sand substrates where 

 46% of the samples and 47% of the specimens were found. 

 The next highest amounts of both samples and specimens 

 occurred in sand-shell substrates where 37 and 32%. respec- 

 tively, were found; silty sand substrates yielded 8% of the 

 samples and 14% of the specimens, while gravel and sand- 

 gravel substrates each contained 2% of the samples but the 

 former contained 3% and the latter 1% of the specimens 

 (Table 193). 



Crassinella sp. Figure 30. 



The NEFC collection contains nine specimens of this taxon 

 from three samples (Table 5). 



Our three samples of this taxon are from the continental 

 shelf; one sample is off Cape Hatteras, N.C., and the other 

 two are northeast of Charleston, S.C. (Fig. 30; Theroux and 

 Wigley footnote 4, table 48). 



Our samples are from water depths between 7 and 25 m with 

 a mean of 14 m. Two-thirds of the samples are in the 0-24 m 

 depth range grouping and the remaining third in the 25-49 m 

 grouping; 56% of the specimens are in the 0-24 m depth range 

 grouping and 44% in the 25-49 m grouping (Table 194). 



The majority of our samples and specimens, 67 and 78%, 

 respectively, occurred in sand while 33% of the samples and 

 22% of the specimens occurred in sand-shell (Table 195). 



Genus Eucrassatella Iredale 1924 



Eucrassatella speciosa (A. Adams 1852). Gibb's clam. Figure 

 44. 



This species occurs from North Carolina to both sides of 

 Florida and the West Indies and is found elsewhere in the 

 Caribbean (Johnson 1934; Abbott 1968, 1974). 



This species is a moderately common to frequent southern 

 form which is represented in our collection by three speci- 

 mens from two samples (Table 5). 



Our samples are from the continental shelf between Cape 

 Fear, N.C., and Charleston, S.C. (Fig. 44: Theroux and Wig- 

 ley footnote 4, table 73). 



This species is a Transatlantic and Carolinian province 

 inhabitant (Dance 1974). 



The reported depth range for Gibb's clam is from 4 to 183 m 

 (Johnson 1934; Abbott 1968). 



The two samples in the NEFC collection are from 25 and 38 

 m of water. This depth range places both samples in the 25-49 

 m depth range grouping. 



Our samples were obtained on a sand substrate. 



Family CARDIIDAE 



Genus Cerastoderma Poli 1795 



Cerastoderma pinnulatum (Conrad 1830). Northern dwarf 

 cockle. Figure 23. 



This species occurs from Labrador to off North Carolina in 

 the Cape Lookout region (Johnson 1934; La Rocque 1953: 

 Abbott 1968, 1974; Morris 1973; Emerson et al. 1976). 



Cerastoderma pinnulatum is a common bivalve which 

 occurs in 4.5% of our samples composing 3% of the total 

 number of specimens in our collection (Table 5). 



35 



