Our suite of samples is from water depths which range 

 between 23 and 458 m with a mean of 106 m. The majority of 

 samples are in the 50-99 m depth range grouping which con- 

 tains 78% of the samples and 88% of the specimens; the 0-24 

 and 25-49 m groupings each contain 4% of the samples, and 3 

 and 4% of the specimens, respectively, while the 100-199 m 

 and 200-499 m groupings each contain 7% of the samples and 2 

 and 3% of the specimens, respectively (Table 294). 



Morris (1951) reported that the fragile spoon clam inhabits 

 sand substrates. 



The distribution of NEFC samples with regard to sediments 

 with decreasing particle size is as follows: 4% of the samples 

 and 3% of the specimens occurred in sand-shell; 37% of the 

 samples and 22% of the specimens in sand; one-third (33%) of 

 the samples and 21% of the specimens occurred in silty sand; 

 1 1 % of the samples and 2 1 % of the specimens occurred in silt ; 

 while 15% of the samples and 34% of the specimens occurred 

 in clay substrates (Table 295). 



Periploma leanum (Conrad 1830). ' ' Lea's spoon clam. Figure 86. 



Lea's spoon clam is distributed from the Gulf of St. Law- 

 rence and Nova Scotia to off North Carolina (Johnson 1934; 

 Morris 1951, 1973;LaRocque 1953; Abbott 1974; Emerson et 

 al. 1976). 



Periploma leanum is an uncommon to fairly common bi- 

 valve; there are 60 specimens of this species from 27 samples 

 in the NEFC Specimen Reference Collection (Table 5). 



Our specimens are from the continental shelf off the coast 

 of Maine, in the Cape Cod region, and the offshore continen- 

 tal shelf and slope waters south of Nantucket Shoals (Fig. 86, 

 Theroux and Wigley footnote 4, table 149). 



The main distribution of this species is in the Boreal and 

 Virginian provinces (Coomans 1962; Gosner 1971). 



The depth range of this species extends from just offshore 

 in moderately shallow water to approximately 29 m (Johnson 

 1934; Abbott 1974). 



Our samples are from depths which range between 1 and 

 135 m with a mean of 48 m. The abundance of samples and 

 specimens with regard to depth range groupings is as follows: 

 33% of the samples and 30% of the specimens are in the 0-24 m 

 grouping: 26% of the samples and 38% of the specimens in the 

 25-49 m grouping; 26% of the samples and 22% of the speci- 

 mens in the 50-99 m grouping and 15% of the samples and 10% 

 of the specimens in the 100-199 m grouping (Table 296). 



The samples yielding our specimens occurred in four sedi- 

 ment types. The majority of samples and specimens occurred 

 in sand substrates which contained 46% of the samples and 

 61% of the specimens; sand-gravel substrates contained 23% 

 of the former and 18% of the latter, while silty sand sediments 

 contained 18% of the samples and 10% of the specimens; clay 

 was the only other sediment type in which these organisms 

 were found and it contained 14% of the samples and 10% of 

 the specimens (Table 297). There are 5 samples containing 11 

 specimens which are unclassified with regard to sediment 

 type. 



"Abbott (1974) has "(Conrad. 1831)" for this species, it should be (Conrad 

 1830), see under References. 



Periploma papyratium (Say 1822). Paper spoon clam. Figure 87. 



The paper spoon clam is distributed from Labrador to 

 Rhode Island and from South Carolina to the Gulf of Mexico 

 (Johnson 1934; Clarke 1962; Morris 1973; Abbott 1974). 



Periploma papyratium is a moderately common bivalve 

 which is normally found in the northern reaches of the study 

 area as reflected by the abundance of samples and specimens 

 intheNEFCcollection. Periploma papyra tium is represented 

 by 2,976 specimens, nearly 3% of the entire collection, from 

 265 samples, again, nearly 3% of the entire collection (Table 

 5). 



Samples in the NEFC collection range from the Nova Sco- 

 tian shelf, along the inner edge of the Gulf of Maine extending 

 out towards the northern edge of Georges Bank and south 

 onto the Southern New England shelf area and the Middle 

 Atlantic Bight region (Fig. 87; Theroux and Wigley footnote 

 4, table 150). 



The paper spoon clam inhabits the Boreal and Virginian 

 provinces (Coomans 1 962) ; Gosner ( 1 97 1 ) placed it only in the 

 Boreal province. 



The published depth range for this species is from 1.8 to 

 2,297 m (Clarke 1962; Abbott 1974). 



The NEFC samples range in depth from 7 to 458 m with a 

 mean of 121 m. In terms of distribution among the depth range 

 groupings there is a general tendency for a decrease in abun- 

 dance with both increasing and decreasing depth range group- 

 ing from the 50-99 m grouping which contains 49% of the 

 samples and 69% of the specimens; next greatest abundance 

 occurs in the 1 00- 1 99 m grouping with 25% of the samples and 

 14% of the specimens; the 25-49 m and the 0-24 m groupings 

 each contain 8 and 1% of the samples, respectively, and 10 

 and 1% of the specimens, respectively, while the 200-499 m 

 grouping contains 17% of samples and 7% of the specimens 

 (Table 298). 



The finer grained substrates contained significantly greater 

 amounts of both samples and specimens of this species than 

 the coarser ones. In order of decreasing particle size, abun- 

 dance is as follows: gravel contained 1% of the samples and 

 0.4% of the specimens; sand-gravel, 2% for samples and 9% 

 for specimens; till, 8% for samples and 14% for specimens; 

 sand-shell substrates had traces of both, 0.4% samples and 

 0.1% specimens, while sand contained 23% for samples and 

 8% of the specimens; silty sand substrates accounted for 28% 

 of the samples and 26% of the specimens; silt contained 10% 

 of the samples and 12% of the specimens; and clay substrates 

 contained the largest amounts, 29% of the samples and 31% of 

 the specimens (Table 299). There is one sample containing 

 one specimen which is unclassified with regard to sediment 

 type. 



Periploma sp. Figure 88. 



There are four specimens from four samples in the NEFC 

 collection which bear the classification Periploma sp. (Table 

 5). 



Samples containing members of this genus are from the 

 Gulf of Maine, the southern part of Georges Bank, and the 

 Southern New England shelf area (Fig. 88; Theroux and 

 Wigley footnote 4, table 151). 



Our samples are from depths which range from 59 to 232 m 

 with a mean of 117 m. The 50-99 m depth range grouping 



54 



