188 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 112 



The male is unknown. 



Remarks: This species cannot with absolute certainty be placed 

 in the genus Hemicyclops without further knowledge of its mouth- 

 parts, but there is good evidence for and apparently none against 

 placing it here. There is also no assurance that the holot3 r pe is 

 mature. 



H. elongalus is very similar to adhaerens and subadhaerens in general 

 characters of bod} 7- and the appendages known. The only important 

 differences appear to be its size, greater length rwidth ratio of the 

 caudal rami and last antennular segment, and the segmentation of 

 the latter appendage. 



Distribution: The only information is that given above. Again, 

 there is insufficient evidence to place the species definitely as an 

 associate of Callianassa, although Wilson's statement that the holo- 

 type occurred in the gill-chamber is more positive than our present 

 knowledge about subadhaerens. But it is possible that elongalus also 

 occurs in burrow water. 



Hemicyclops arenicolae, new species 



Figures 9-10 



Specimens examined : Wellfleet Harbor, Cape Cod, Massachusetts, 

 26 females, 27 males, and 13 juveniles from burrows and body surface 

 of 4 Arenicola cristata Stimpson, sand and rubble beach, C. M. Moore 

 and M. Pettibone, July 3, 1954; 2 females and 2 males were dis- 

 sected; figures 9a-c and j-p and 10 are based on one of each sex. 

 Lackey's Bay, Woods Hole, Massachusetts, 3 females, 4 males, and 

 1 juvenile from the same host, Moore and Pettibone, July 31, 1954; 

 1 female and 1 male of this lot were dissected; figure 9d-e is from 

 this female. 



Types: The holotype, USNM 101732, a dissected female, and the 

 allotype male, USNM 101733, are both from the Wellfleet sample. 

 Para types from Wellfleet, 21 females and 21 males, and, from Lackey's 

 Bay, 2 females and 3 males, have also been deposited in the U.S. 

 National Museum, Nos. 101370 and 101369 respectively. 



Figup.e 8. — Hemicyclops elongalus Wilson, female: a, Habitus, dorsal aspect, b, Habitus, 

 lateral aspect, c, Right antennule, ventral (posterior) view, d, Left maxilliped, ventral 

 (posterior) view, e, Left first swimming leg with coxal plate, ventral (anterior) view. 

 /, Left second swimming leg with part of coxal plate, ventral (anterior) view, g, Left 

 third swimming leg with part of coxal plate, ventral (anterior) view, h, Left fourth 

 swimming leg, ventral (anterior) view, i, Left fifth leg, dorsal view. /, Left sixth leg, 

 dorsal view, k, Left caudal ramus, dorsal view. All appendages were drawn in situ. 

 Scale A applies to a and b; B to d and /; and C to the remainder. 



