ART. 5. NORTH AMERICAN PARASITIC COPEPODS WILSON. 65 



ciall^^ in the lobes of the dorsal plates and inside the bases of the 

 swimming legs. 



Internal speciiic characters of male. — Digestive canal and nervous 

 system similar to those of the female. Testes situated at the pos- 

 terior end of the cephalothorax near the dorsal surface, with the 

 sperm ducts leading back to the spermatophore receptacles in the 

 genital segment. These receptacles occupy practically the whole of 

 the genital segment, and each opens on the ventral surface near the 

 center of its half of the posterior margin. Just in front of the re- 

 ceptacle the walls of the sperm duct are thickened and become glandu- 

 lar for the secretion of the cement substance which forms the out- 

 side wall or case of the spermatophore. 



The excretory glands are more difficult to locate than in the 

 female, and it is impossible to recognize them with certainty in any 

 sections thus far examined. 



{atlantica^ of or belonging to the Atlantic Ocean.) 



Remarks. — This species was found clinging to the very tips of the 

 gill filaments, and while the total number of specimens is large, the 

 yield from each fish was small. Four of the largest sharks exam- 

 ined contributed only three specimens, two males and a female. 



When removed and placed in water both sexes are very restless 

 and keep up a constant motion of all their appendages. The male by 

 reason of the plumose setae on his swimming legs is able to lack him- 

 self about, and even to swim in a bungling fashion, but the female 

 simply rolls around, and is practically helpless. 



This species has already been contrasted with the one obtained 

 from the hammer-head shark in the West Indies on page 239 of vol- 

 ume 44 of these Proceedings. The sunplest way to tell these two 

 species is by the presence or absence of a knob on either margin of 

 the cephalothorax and by the visibility or invisibility of the fifth 

 legs in dorsal view. 



Genus EUDACTYLINA P. J. van Beneden. 



Eudactylina Beneden, Bull. Acad. Roy. de Belgique, vol. 20, 1853, p. 235. 

 Eudactylina Olsson, Lunds Univ. Arsskrift. vol. 5. 18GS-9, No. 8, p. 24. 

 Eudactylina Valle, Boll. Soc. Adriatica Sci. Nat. Trieste, vol. 6, 1880, p. 67. 

 Eudactylina T. and A. Scott, British Parasitic Copepoda, 1913, p. 125. 



Generic characters of female. — Head fused with first thorax seg- 

 ment and covered more or less completely with a carapace, the latter 

 usually emarginate posteriorly. Four free thorax segments, without 

 dorsal plates or lateral processes, the first three with biramose swim- 

 ming legs, the last one (fifth segment) with uniramose legs. Genital 

 segment considerably smaller than the fifth segment; abdomen stiD 

 smaller and from one- to three-jointed. 



