Our samples are from depths which range between 7 and 

 100 m with a mean of 72 m. The majority of both samples and 

 specimens are in the 50-99 m depth range grouping, which 

 contains 81% of the samples and 87% of the specimens; the 

 25-49 m grouping contains 10% of the samples and 4% of the 

 specimens, while each of the 0-24 m and 100-199 m groupings 

 contain 5% of the samples but 6 and 2%, respectively, for 

 specimens (Table 34). 



Morris (1973) indicated that this species prefers muddy 

 substrates. Our samples were obtained from nearly all the 

 sediment types considered in this report with the exception of 

 sand and clay. Abundances of samples and specimens with 

 regard to sediment type are as follows: gravel substrates 

 contained 33% of the samples and 25% of the specimens, 

 while sand-gravel yielded 28% of the samples and 32% of the 

 specimens; three sediment types, till, silty sand, and silt, each 

 contained 6% of the samples but 2.3% of the specimens for 

 both till and silty sand, and 7% of the specimens occurred in 

 silt; both shell and sand-shell each contained 11% of the 

 samples and 27 and 5% of the specimens, respectively (Table 

 35). There are three samples containing three specimens 

 which are unclassified with regard to sediment type. 



Yoldia regularis Verrill 1884. Figure 118. 



Published distributional information for this species shows 

 it to occur from Newfoundland to off Martha's Vineyard. 

 Mass. (Johnson 1934; Ockelmann 1958: Abbott 1974). 



There are 43 specimens from 6 samples of this species in the 

 NEFC Specimen Reference Collection (Table 5). The NEFC 

 suite of samples is from the Gulf of Maine, ranging from south 

 of Grand Manan Island south to Cape Cod Bay (Fig. 118: 

 Theroux and Wigley footnote 4. table 212). 



Both Johnson (1934) and Gosner (1971) listed the depth 

 range for this species as being 179 to 639 m. 



The NEFC samples are from water depths which range 

 between 44 and 142 m with a mean of 83 m. The 50-99 m depth 

 range grouping contains 82% of the samples and 76% of the 

 specimens, while each of the 25-49 m and 100-199 m groupings 

 contain 9% of the samples but 2 and 21%. respectively, of the 

 specimens (Table 36). 



Specimens of Yoldia regularis were obtained from three 

 sediment types, all of which were the finer grained substrates. 

 The majority of samples were in silty sand which contained 

 55% of the samples, but only 21% of the specimens: silt. 

 however, while containing 36% of the samples provided the 

 majority of specimens 57%; clay sediments contained 9% of 

 the samples and 21% of the specimens (Table 37). 



Yoldia sapotilla (Gould 1841). Short yoldia. Figure 119. 



This species, although primarily a northern or Arctic in- 

 habitant ranges from Arctic seas and Labrador and New- 

 foundland to approximately North Carolina (Johnson 1934; 

 Morris 1951. 1973:LaRocque 1953: Ockelmann 1958: Abbott 

 1968. 1974). 



Yoldia sapotilla is common and is represented in the NEFC 

 collection by 279 samples, constituting 2.5% of the total num- 

 ber of samples, containing 2.128 specimens or nearly 2% of 

 the total number of specimens (Table 5). The NEFC samples 

 occur in the Gulf of Maine and Georges Bank with a large 

 concentration of them on the Southern New Ensland shelf 



and upper slope regions ranging south to approximately north 

 and east of the entrance to Chesapeake Bay (Fig. 1 19; Ther- 

 oux and Wigley footnote 4. table 213). 



Coomans (1962) reported this species as an Arctic. Boreal, 

 and Virginian province inhabitant, while Gosner (1971) 

 placed it in the Boreal and Virginian provinces. 



This species is considered to be a moderately deep water 

 inhabitant occupying depths which range between 7 and 250 

 m (Abbott 1968; Porter 1974). 



Our samples are from depths which range between 15 and 

 421 m with a mean of 109 m. The majority of both samples and 

 specimens are in the 50-99 m depth range grouping which 

 contains 55% of the samples and 66% of the specimens; the 

 100-199 m grouping contains 21% of the samples and 17% of 

 the specimens, while the 200-499 m grouping contains 14% of 

 the samples and 8% of the specimens, smaller amounts are in 

 the shallower depth range groupings. 0-24 and 25-49 m which 

 contain 0.7 and 10%. respectively, for samples and 0.1 and 

 8.2%. respectively, for specimens (Table 38). There is 1 sam- 

 ple containing 148 specimens for which no depth information 

 is available. 



Morris (1951) and Abbott (1968) both reported this species 

 as normally found in mud habitats. 



The only sediment type considered in this report in which 

 this species was not found was gravel; it did, however, prefer 

 the finer grained substrates over the coarser ones. Abun- 

 dances in terms of decreasing particle size are as follows: 

 sand-gravel substrates contained 0.4% of the samples and < 

 0.1% of the specimens, till substrates, 5% of the samples and 

 3% of the specimens, shell substrates, 0.4% of the samples 

 and < 0.1% of the specimens, while sand-shell substrates 

 contained 0.7% of the samples and 0.2% of the specimens; 

 sand, however, contained 28% of the samples and 25% of the 

 specimens, while silty sand contained 33% of the samples and 

 38% of the specimens; silt substrates contained 6% of the 

 samples and 7% of the specimens, while clay contained 26% 

 of the samples and 27% of the specimens (Table 39). There are 

 9 samples containing 158 specimens which are unclassified 

 with regard to sediment type. 



Yoldia thraciaeformis Storer 1838. Broad yoldia. Figure 120. 



The broad yoldia occurs in both the Atlantic and Pacific 

 Oceans; in the Atlantic it is distributed from the Arctic Ocean 

 and Greenland to the New England coast at Massachusetts; in 

 the Pacific it ranges from the Arctic Ocean to Puget Sound, 

 Wash. (Johnson 1934; Morris 1951, 1973; La Rocque 1953; 

 Ockelmann 1958; Abbott 1968, 1974). 



Yoldia thraciaeformis is moderately common and is repre- 

 sented in the NEFC collection by 158 specimens from 46 

 samples (Table 5). 



The NEFC samples are from the western portion of the 

 Gulf of Maine ranging from south of Grand Manan Island 

 south into Cape Cod Bay (Fig. 120; Theroux and Wigley 

 footnote 4, table 214). 



Coomans (1962) reported the distribution of this species to 

 be in the Arctic, Boreal, and Virginian provinces while Gos- 

 ner (1971) placed it in the Boreal province. The depth distribu- 

 tion of this species ranges from shallow to deep water with a 

 range of approximately 18 to 418 m (Johnson 1934; Abbott 

 1974; Porter 1974). 





