3% of the samples and 15% of the specimens; the 25-49 m 

 grouping, 10% of the former and 2% of the latter: the 50-99 m 

 grouping contains 7 and 2%. respectively, while the 100- 199 m 

 grouping contains 12% of the samples and 20% of the spe- 

 cimens; the 200-499 m grouping contains 16 and 3%, respec- 

 tively: the 500-999 m grouping 12 and 11%. respectively, and 

 the deepest grouping, 2.000-3,999 m, contains 12% of the 

 samples and 10% of the specimens (Table 14). 



Shell was the only sediment type which did not contain any 

 members of this taxon. In terms of decreasing particle size, 

 distribution of samples and specimens is as follows: gravel 

 contained 1% of the samples and 0.3% of the specimens: 

 sand-gravel 2 and 19%, respectively; till substrates 1 and 2%, 

 respectively, while sand-shell contained 6% of the samples 

 and 2% of the specimens: sand sediments contained 17% of 

 the samples and 5% of the specimens, while silty sand was 

 equal with 30% for samples and specimens: silt contained the 

 largest amounts of both samples and specimens with 32 and 

 37%, respectively, while the finest substrate, clay, contained 

 12% of the samples and 6% of the specimens (Table 15). There 

 are 4 samples containing 200 specimens which are unclassi- 

 fied with regard to sediment type. 



Family MALLETIIDAE 



Genus Malletia Des Moulins 1832 



Malletia obtusa G. O. Sars 1872. Blunt nutshell. Figure 60. 



This nutshell is distributed from off Massachusetts to North 

 Carolina in the western Atlantic and from Norway to off West 

 Africa in the eastern Atlantic; it is also quite widely distrib- 

 uted in the Arctic and occurs in the Mediterranean and the 

 Cape Verde Islands as well as the Canary Islands (Johnson 

 1934; Ockelmann 1958; Clarke 1962; Morris 1973; Abbott 

 1974). 



The blunt nutshell is a deep water inhabitant which is 

 represented by 145 specimens from 38 samples in the NEFC 

 collection (Table 5). 



Our samples are from the continental slope and upper con- 

 tinental rise between Nova Scotia and Cape Hatteras, N.C. 

 (Fig. 60, Theroux and Wigley footnote 4, table 105). 



The bathymetric range for this organism is 366 to 3,259 m 

 (Johnson 1934; Clarke 1962). 



The NEFC sample suite is from water depths ranging be- 

 tween 1,045 to 2,975 m with a mean of 1,998 m. 



Fifty-three percent of the samples and 66% of the speci- 

 mens are in the 1 ,000-1 ,999 m depth range grouping, and 47% 

 of the samples and 34% of the specimens are in the 2,000-3,999 

 m grouping (Table 16). 



Due to the deep dwelling habits of this species they were 

 only found in sediment types of small particle size. The major- 

 ity of samples (53%) and specimens (62%) occurred in silt. 

 Clay substrates contained 26% of the samples and 21% of the 

 specimens, and silty sand substrates contained 21% of the 

 samples and 17% of the specimens (Table 17). 



Genus Saturnia Sequenza 1877 



Saturnia subovata Verrill and Bush 1897. Ovate nut shell. Fig- 

 ure 97. 



This species is distributed from Nova Scotia to North Caro- 

 lina (Johnson 1934; LaRocque 1953; Morris 1973). 



Saturnia subovata is represented in the NEFC Specimen 

 Reference Collection by 70 specimens from 22 samples (Table 

 5). 



The NEFC samples are from the upper continental slope on 

 the northeast peak of Georges Bank to the region between 

 Delaware and Chesapeake Bays (Fig. 97; Theroux and Wigley 

 footnote 4, table 171). 



Johnson (1934) and La Rocque (1953) reported the depth 

 range for this species as extending from 229 to 3,168 m. 



Our samples are from deep water between 650 and 2,520 m 

 with a mean of 1,911 m. The 500-999 m depth range grouping 

 contains 5% of the samples and 4% of the specimens, while 

 the 1,000-1 ,999 m grouping contains 46% of the samples and 

 57% of the specimens; the 2,000-3,999 m grouping contains 

 50% of the samples and 39% of the specimens (Table 18). 



The ovate nut shell was found in the finer grained sediment 

 types. Twenty-three percent of the samples and 23% of the 

 specimens occurred in silty sand, while 64% of the samples 

 and 59% of the specimens were found in silt; clay substrates 

 contained 14% of the samples and 19% of the specimens 

 (Table 19). 



Family NUCULANIDAE 



There are 98 samples in the NEFC collection containing 834 

 specimens which are classified to the family level of Nucula- 

 nidae (Table 5). 



The samples containing this taxon range from the upper 

 continental slope and lower continental shelf off Atlantic 

 City, N.J., to south of Miami, Fla. (Fig. 79; Theroux and 

 Wigley footnote 4, table 133). 



Our samples range in depth from 45 to 2,680 m with a mean 

 of 404 m. The majority of both samples (56%) and specimens 

 (73%) are in the 200-499 m depth range grouping and diminish 

 on either side of this grouping with increasing and decreasing 

 water depth range. The 100-199 m grouping contains 10% of 

 the samples and 18% of the specimens, the 50-99 m grouping. 

 4% of the samples and 1% of the specimens, and the 25-49 m 

 grouping, the shallowest in which they are grouped, contains 

 3% of the samples and 0.5% of the specimens, the 500-999 m 

 grouping contains 25% of the samples and 8% of the speci- 

 mens, and the 2,000-3,999 m grouping contains 2% of the 

 samples and 0.4% of the specimens (Table 20). 



Members of this taxon were absent from two sediment 

 types, sand-gravel and till. The majority of both samples and 

 specimens occurred in sand, where 34% of the former, and 

 38% of the latter were found; silty sand substrates contained 

 29% of the samples, and 36% of the specimens, while silt 

 substrates contained 20% of the former and 19% of the latter; 

 the finest grained substrate, clay, contained 2% of the sam- 

 ples and 0.4% for specimens; sand-shell substrates contained 

 10% of samples and 4% of the specimens, while shell con- 

 tained 2% for samples and 2% for specimens; the coarsest 

 substrate, gravel, contained 3% for samples and 1% for speci- 

 mens (Table 21). 



Genus Nuculana Link 1807 



Nuculana acuta (Conrad 1831). Pointed nut clam. Figure 75. 



The pointed nut clam is found in both the North Atlantic 

 and North Pacific Oceans. In the Atlantic it ranges from Cape 

 Cod to Texas and the West Indies, and on to Brazil, while in 



