curred on sand-gravel (1,600/m'), but the largest 

 number of samples (81/106) occurred on sand bottoms. 



Unciola irrorata Say 1818 



Geographic Distribution. This species has been re- 

 ported from the Gulf of St. Lawrence to South Carolina 

 along the eastern coast of North America (Shoemaker 

 1945b). It was ubiquitous in our study area occurring in 

 216 samples from 189 stations between Cape Cod and 

 Cape Hatteras (Fig. 10). The density of this species 

 ranged between 2/m- and 4,900/m- with a mean of 

 100/m-. Its mean density decreased from 220/m- in 

 southern New England to 40/m-' in the New York Bight 

 to 20/m^ in the Chesapeake Bight, showing a clear trend 

 of decreasing abundance from north to south. 



Bathymetric Distribution. Shoemaker (1945b) 

 reported (J. irrorata has previously been collected be- 

 tween low water and 300 m. We collected this species 

 between 6 and 500 m. However, the majority of the rec- 

 ords (169/216) and the highest mean densities (70- 

 2.30/m2) were found between 10 and 70 m (Table 21). 

 The bathymetric distribution of this species did not 

 change with latitude. 



Unciola laticomU Hansen 1887 



According to Shoemaker (1945b), this species occurs 

 in deep water (100-3,000 m) between Nova Scotia and 

 Virginia. We collected a single specimen of this abyssal 

 amphipod at 1,995 m on a silt bottom east of Virginia 

 (Fig. 11). 



Unciola leucopis (Kri^yer) 1845 



This arctic boreal species is widely distributed in the 

 North Atlantic and has previously been recorded as far 

 south as Georges Bank off the east coast of North 

 America (Shoemaker 1945b). Our collections from nine 

 stations distributed along the outer continental shelf 

 and upper continental slope between Massachusetts 

 and New Jersey (Fig. 11) extend the range of this species 

 to the south. These records were distributed between 62 

 and 450 m on sand (8/9) and silly sand (1/9) sediments. 

 This cold-water species shows some evidence of south- 

 ern submergence since the five northernmost records are 

 in <100 m and the four southernmost records are below 

 200 m. 



Table 21.— Bathymetric distribution of Unciola irro- 

 rata in samples from Middle Atlantic Bight. 



Sediment Relationship. According to Bousfield (1973), 

 this species is usually found on coarse to medium sand 

 sediments. We collected U. irrorata on a wide variety of 

 sediment types ranging from sand-gravel to silt-clay 

 (Table 22). The largest number of samples (159/216) 

 came from sand bottoms, and the highest mean density 

 was found on sand-gravel sediments. 



Unciola serrata Shoemaker 1945 



Shoemaker (1945b) found this species in shallow 

 coastal waters from Vineyard Sound to Georgia. In our 

 collections, U. serrata occurred in low densities (4- 

 100/m^) at five stations between Vineyard Sound and 

 Delaware Bay (Fig. 11). It was found between 16 and 54 

 m on gravel, shelly sand, sand, and clayey silt bot- 

 toms. 



Unciola apicata Shoemaker 1945 



Shoemaker (1945b) gave the geographic range of this 

 species as New Jersey to Florida. We collected U. 

 spicata at nine stations along the outer edge of the con- 

 tinental shelf between Long Island and Cape Hatteras 

 (Fig. 11). Shoemaker (1945b) found this species be- 

 tween 40 and 800 m, but the majority of his records oc- 

 curred around 200 m. In our collectons, U. spicata oc- 

 curred in low densities (10/m^) between 80 and 194 m on 

 sand (5/10), silty sand (4/10), and shell (1/10) bot- 

 toms. 



Table 22. — Sediment associations of Unciola irrorata 

 in samples from Middle Atlantic BiKht. 



Unciola sp. A 



An undescribed species of Unciola was collected in 11 

 samples from 10 stations on the out«r portion of the con- 

 tinental shelf (Fig. 11). Nine of the 10 stations were 

 north of New Jersey indicating this species probably has 

 a subarctic-boreal distribution. Its density was low at all 

 10 stations, ranging between 2/m^ and 50/m^ with a 

 mean density of 20/m^ We collected it between 90 



20 



