Gosner (1971) placed this species in the Boreal province. 



The bathymetric range of this species is from just below tide 

 mark level to 275 m (Abbott 1974). 



The samples in the NEFC collection range in depth be- 

 tween 38 and 366 m with a mean of 159 m. The majority of both 

 samples and specimens are in the 100-199 m depth range 

 grouping which contains 44% of the samples and 40% of the 

 specimens: the 200-499 m grouping contains 29% of the sam- 

 ples and 31% of the specimens, while the 50-99 m grouping 

 contains 23 and 27%, respectively; the smallest amounts of 

 both samples and specimens are in the 25-49 m grouping with 

 4% of the former and 3% of the latter (Table 28). 



Among the nine sediment types considered in this report, 

 shell was the only one which did not contain any members of 

 this species. In order of decreasing particle size, distribution 

 of samples and specimens is as follows: 8% of the samples and 

 6% of the specimens occurred in gravel, 7% of the former and 

 3% of the latter in sand-gravel, while till contained 21% of the 

 samples and 33% of the specimens; sand-shell substrates 

 contained < 1% of the samples and 1% of the specimens, 

 sand, 6% of the former and 3% of the latter; silty sand sub- 

 strates, however, contained 28% of the samples and 29% of 

 the specimens ; the two finest grained substrates, silt and clay, 

 contained 8 and 21%, respectively, for samples, and 9 and 

 17%, respectively, for specimens (Table 29). There are 9 

 samples containing 55 specimens which are unclassified with 

 regard to sediment type. 



Nuculana sp. Figure 78. 



The NEFC Specimen Reference Collection contains 448 

 specimens from 84 samples which are identified to the generic 

 level of Nuculana sp. (Table 5). 



Samples containing members of this genus are distributed 

 from the central Gulf of Maine south to Key West, Fla. , with a 

 major gap occurring in the Middle Atlantic Bight Region (Fig. 

 78; Theroux and Wigley footnote 4, table 132). 



The NEFC samples range in depth from 15 to 458 m of 

 water with a mean of 141 m. The distribution of samples and 

 specimens among the various depth range groupings is as 

 follows: 2% of the samples and 0.7% of the specimens are in 

 the 0-24 m depth range grouping, while 12% of the former and 

 4% of the latter are in the 25-49 m grouping. The 50-99 m 

 grouping contains 21% of the samples and 61% of the speci- 

 mens, with the 100-199 m grouping containing 42% of the 

 former and 28% of the latter; the last depth range grouping in 

 which these organisms are arrayed is the 200-499 m depth 

 range grouping which contains 23% of the samples and 7% of 

 the specimens (Table 30). 



No member of this genus was found in either sand-gravel or 

 till substrates; however, specimens were found in all other 

 substrate types considered in this report. In order of decreas- 

 ing particle size, the samples and specimens were distributed 

 as follows: gravel contained 2% of the samples and 3% of the 

 specimens, shell, 2% of the former and 1% of the latter; 

 sand-shell substrates contained 17% of the samples and 28% 

 of the specimens, while sand contained 24% of the former and 

 43% of the latter; silty sand contained 39% of the samples and 

 22% of specimens, silt, 1% for samples, 0.2% for specimens, 

 and clay, the finest grained sediment type, contained 13% of 

 the samples and 4% of the specimens (Table 31). There are 

 two samples containing two specimens which are unclassified 

 with regard to sediment type. 



Genus Yoldia Moller 1842 

 Yoldia limatula (Say 1831). File yoldia. Figure 117. 



This species is widely distributed, occuring in both the 

 North Atlantic and North Pacific Oceans. In the Atlantic it 

 ranges from the Gulf of St. Lawrence and Nova Scotia, south 

 to North Carolina, while in the Pacific it ranges from Alaska 

 south to San Diego, Calif. ; it also occurs in the eastern Atlan- 

 tic (Johnson 1934; La Rocque 1953; Ockelmann 1958; Abbott 

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



The file yoldia is represented in the NEFC collection by 375 

 specimens from 37 samples (Table 5), from the northern sec- 

 tor of the study area, ranging from off the coast of Maine, in 

 the Gulf of Maine, on the southeastern part of Georges Bank, 

 but primarily inshore from the Cape Cod region south into 

 Chesapeake Bay (Fig. 117; Theroux and Wigley footnote 4, 

 table 210). 



The zoogeographic distribution of this species is in the 

 Boreal and Virginian provinces according to Coomans (1962) 

 and Gosner (1971); Dance (1974) placed it in the Transatlantic 

 and Boreal provinces in eastern North America, and in the 

 Arctic province. 



This species is primarily a shallow water inhabitant, 

 occupying water depths from just below the low water mark in 

 bays and inlets in nearshore areas out to approximately 23 m 

 (Abbott 1968, 1974; Porter 1974). 



Our samples are from water depths which range from to 

 121 m with a mean of 29 m. The majority of both samples and 

 specimens are in the shallower depth range groupings with 

 60% of the samples and 64% of the specimens occurring in the 

 0-24 m grouping and 30% of the samples and 29% of the 

 specimens in the 25-49 m grouping; the 50-99 and 100-199 m 

 groupings each contain 5% of the samples and 6.7% and 0.5% 

 of the specimens, respectively (Table 32). 



Morris (1973) and Emerson et al. (1976) both reported this 

 species as a mud bottom inhabitant. 



Our samples were obtained from the finer grained sedi- 

 ments which ranged from sand down to clay. Sand contained 

 70% of the samples and 40% of the specimens; silty sand 

 substrates yielded 23% of the samples and 22% of the speci- 

 mens, while silt and clay each contained 3% of the samples 

 but 38% and 0.3% of the specimens, respectively (Table 33). 

 There are 7 samples containing 33 specimens which are un- 

 classified with regard to sediment type. 



Yoldia myalis (Couthouy 1838). Comb yoldia. Figure 118. 



The comb yoldia is found in both the North Atlantic and 

 North Pacific Oceans. In the Atlantic it ranges from Hudson 

 Strait in Labrador to Massachusetts while in the Pacific it 

 ranges from Alaska to Puget Sound. Wash. (Johnson 1934: 

 Morris 1951, 1973; La Rocque 1953; Ockelmann 1958:Abbott 

 1974). 



There are 47 specimens of this species in the NEFC collec- 

 tion from 21 samples (Table 5). 



Our samples are from the Scotian Shelf and along the coast 

 of Maine (Fig. 1 1 8 ; Theroux and Wigley footnote 4. table 211). 



The comb yoldia is an inhabitant of the Boreal province 

 (Gosner 1971). 



The depth distribution of this species is from moderately 

 shallow water to approximately 146 m (Morris 1973: Abbott 

 1974). 



