COPEPODS OF THE WOODS HOLE REGION 389 



In the second legs the two terminal segments of the endopod are 

 fused with no trace of a groove between them, but with a transverse 

 row of spinules where the groove should be, similar to those along 

 the distal margins of the other segments in both rami. These two 

 second-leg rami are about equal in length, the endopod with four 

 apical, one outer, and five inner setae, the exopod with two apical, 

 six outer, and five inner setae. 



In the fifth leg the basal segment is one-half wider than the ter- 

 minal and carries at the center of its inner margin a short filiform 

 seta thickened at its base. The distal segment is four times as long 

 as wide, slightly narrowed distally, with four small denticles on the 

 outside margin near the tip. The end is obliquely truncated, with a 

 short spine at the outer corner and a long curved seta at the inner 

 corner. Total length, 2-2.5 mm. 



Male. — Body slender and cylindrical, but curved ventrally like that 

 of the female; head separated from the first segment, wider than 

 long, with rounded lobes at the posterior corners. First thoracic 

 segment very short and only two-thirds as wide as the head ; second, 

 third, and fourth segments about the same length, which is twice 

 that of the first segment, and tapering regularly backward; fifth 

 segment the same length as the first and narrower than the fourth. 



Urosome 5-segmented, tapered regularly backward; anal segment 

 with a small notch at the center of the posterior margin ; caudal rami 

 as long as the last two segments combined, slender, slightly curved 

 like parenthesis marks, each with two minute apical spines. An- 

 tennae, mouth parts, and swimming legs similar to those of the fe- 

 male. Total length, 0.75 mm. 



Remarks. — This species can be most easily recognized by the struc- 

 ture of the second antennae and the fifth legs. The ascidian that 

 serves as its host is fairly abundant around Woods Hole, and there is 

 every reason to believe that further examination would reveal not 

 only this but also other commensals. This is one of the directions in 

 which the search for copepods within the present area has been com- 

 paratively quite limited; hence the prospects for further efforts are 

 exceptionally good. 



DOROPYGUS PULEX Thorell 



FiGiXBE 239 



Doropygus pulex Thobkt.t., Kongl. Vet. Akad. Handl., vol. 3, no. 8, p. 46, pi. 6, 

 1859. 



Occurrence. — Two females were obtained from a Molgula papillosa 

 Verrill, dredged in 6 fathoms off Marthas Vineyard on a stony 

 bottom. 



Distribution. — Mediterranean (Brian, Buchholz) ; coast of France 

 (Canu, Hesse) ; Bohusliin (Aurivillius) ; British seas (T. Scott) ; 

 Arctic Ocean (Thorell). 



