This is a common, small bivalve which is well represented 

 in the NEFC collection which contains 3,474 specimens, 

 approximately 3% of the entire collection, from 149 samples, 

 representing 1% of the entire collection (Table 5). 



All of our samples are in the northern sector of our study 

 area, occupying the periphery of the Gulf of Maine, the Sco- 

 tian Shelf, and Georges Bank to deep slope water areas south 

 of Cape Cod, Mass. (Fig. 48: Theroux and Wigley footnote 4, 

 table 79). 



The zoogeographic distribution of this species, according 

 to several authors, is as follows: Ockelmann (1958) listed it as 

 occupying the Panarctic-Boreal and Mediterannean-Atlantic 

 provinces, stating that it is probably cosmopolitan and cir- 

 cumpolar; Clarke (1962) listed it as occupying the Panarctic 

 and Boreal provinces; Coomans (1962) placed it in the Arctic- 

 boreal, Virginian, Caribbean, Carolinian, and Celtic pro- 

 vinces; Gosner (1971) placed it in the Boreal and Virginian 

 provinces, while Dance (1974) placed it in the Mediterannean, 

 Atlantic, Transatlantic, and Caribbean provinces. 



The Arctic saxicave enjoys a wide bathymetric range 

 occurring from intertidal and littoral regions out to 366 m in 

 the northwest Atlantic (Johnson 1934; Abbott 1968, 1974). 

 Ockelmann (1958) reported it as occurring from down to 

 2,190 m at West Ireland and mentions that dead shells are 

 found in the North Atlantic down to about 2,380 m. Clarke 

 (1962) reported it as occurring between and 2,968 m in 

 depth. 



Our samples range from 18 to 232 m in depth with a mean of 

 81 m. Fifty-one percent of the samples and 24% of the speci- 

 mens are in the 50-99 m depth range grouping while 23% of the 

 samples containing 69% of the specimens are in the 25-49 m 

 grouping; the 100-199 m grouping contains 22% of the samples 

 but only 5% of the specimens; the 200-499 m grouping con- 

 tains 3% of the samples but only 0. 1% of the specimens, while 

 the shallowest depth range grouping, 0-24 m contains 2% of 

 the samples and 2% of the specimens (Table 274). 



Morris (1951) reported that the Arctic saxicave may be 

 found in clay and limestone substrates while Abbott (1968, 

 1974) reported it occurring among kelp holdfasts and in rock 

 crevices and also that it has been found in sponges. 



Our samples were found in all of the 9 substrate types 

 considered in this report. Chief among substrate types is 

 gravel which contained 29% of the samples and 61% of the 

 specimens, sand-gravel contained 24% of the samples and 

 20% of the specimens. There is a general tendency of decreas- 

 ing abundance, both in terms of samples and specimens, with 

 decreasing sediment particle size. Both till and sand sub- 

 strates contained 12% of the samples but only 4 and 10% of the 

 specimens, respectively. In order of diminishing abundance, 

 silty sand contained 8%, clay 5%, shell 3%, and silt 2% of the 

 samples, and lowered specimen amounts as well (Table 275). 

 Thirty-two samples containing 12 1 specimens are unclassified 

 with regard to sediment type. 



Hiatella striata Fleuriau 1802. Figure 49. 



Hiatella striata is represented in the NEFC collection by 

 eight specimens from two samples (Table 5). 



Our two samples are from the western end of Georges Bank 

 east of Great South Channel (Fig. 49; Theroux and Wigley 

 footnote 4, table 80). 



Porter (1974) reported a + 1 m depth range for this species. 



Our samples containing Hiatella striata are from 49 and 70 

 m water depth. The 25-49 m and 50-99 m depth range group- 

 ings each contain 50% of both samples and specimens. 



No information with regard to sediment type is available for 

 the two samples in our collection. 



Genus Panomya Gray 1857 

 Panomya arctica (Lamarck 1818). Arctic rough mya. Figure 83. 



The Arctic rough mya is circumpolar and inhabits both the 

 North Atlantic and North Pacific Oceans. In the Atlantic it 

 ranges from Arctic seas to Chesapeake Bay, while in the 

 Pacific it occurs from Unalaska to Point Barrow. Alaska; it is 

 also known from northern European waters (Johnson 1934; 

 Morris 1951, 1973; Tebble 1966; Abbott 1974). 



Panomya arctica is a common northern seas bivalve that is 

 represented in the NEFC collection by 64 specimens from 19 

 samples (Table 5). 



Our samples are from the Gulf of Maine region with one 

 sample occurring in upper continental slope waters south and 

 east of Long Island. N.Y. (Fig. 83; Theroux and Wigley 

 footnote 4, table 142). 



Coomans (1962) placed this species in the Arctic. Boreal, 

 and Virginian provinces in the western Atlantic, and in the 

 Celtic province in Europe. 



The depth distribution of this species ranges from approx- 

 imately 46 m down to 600 m (Johnson 1934; Abbott 1974). 



Our samples range in depth between 38 and 293 m with a 

 mean of 126 m. The majority of both samples and specimens 

 are in the 50-99 m depth range grouping which contains 53 and 

 78%, respectively; next largest amounts occur in the 100-199 

 m grouping which contains 26 and 14%, respectively; there 

 are 16% of samples and 6% of specimens in the 200-499 m 

 grouping; the shallowest depth range is the 25-49 m grouping 

 which contains 5% of the samples and 2% of the specimens 

 (Table 276). 



This species inhabits mud, gravelly mud, and sandy gravel 

 substrates (Morris 1951, 1973; Tebble 1966; Abbott 1974). 



Our samples were obtained from a variety of sediment 

 types including: silty sand which contained the majority of 

 samples (33%) but only 10% of the specimens; till, however, 

 contained the majority of the specimens (73%) but 25% of the 

 samples: gravel contained 17% of the samples and 6% of the 

 specimens; shell, sand, and clay each contained 8% of the 

 samples but 4, 2, and 4% of the specimens, respectively 

 (Table 277). There are 7 samples containing 16 specimens 

 which are unclassified with regard to sediment type. 



Family PHOLADIDAE 

 Genus Barnea Risso 1826 



Barnea truncata (Say 1822). Fallen angel wing. Figure 17. 



This species enjoys a wide distribution along our shores 

 ranging from Newfoundland, along the entire U.S. east coast 

 into the Gulf of Mexico and south to Brazil; it also occurs in 

 the West Indies and from Senegal to the Gold Coast in West 

 Africa (Johnson 1934: La Rocque 1953; Ockelmann 1958: 

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



The NEFC collection contains 83 specimens from 4 repli- 

 cate samples of this common and locally abundant species 

 (Table 5). 



50 



