DESCRIPTIONS OF PARASITIC COPEPODA BELONGING TO THE 

 GENERA PANDARUS AND CHONDRACANTHUS (WITH SEVEN 



PLATES). 



By RICHAKD RATHBUN. 



Genus PANDAKUS Leach. 



Pandarus sinuatus Say, Journ. Phila. Acad., i, pp. 436-437, 1817. 



Fandarus, sp., Smith, Eept. U. S. Comm. Fish and Fisheries, part 1, p. 576 

 (282), pi. vii, fig. 31, 1873 (1874). 



Phite V, fig. 2 ; plate VI, figs. 1-8; plate VII, figs. 1-8.) 



In 1817, Say described, under the above name, a species of parasitic 

 copepod, which he stated to be of common occurrence on the dog-fish, 

 Sqnalis eanis ? Mitchell. His description, though brief and unsatisfac- 

 tory, evidently applies to a species of Pandarus which has frequently 

 been taken from specimens ofc the dog-fish (Mustelus cams), sand-shark 

 {Carcharms americanus), and Atwood's shark {Carcharodon Atwoodi), 

 collected in the viciuity of Wood's Holl, Mass., by the U. S. Fish Com- 

 mission. The specimens from these several species of sharks differ 

 slightly from one another in certain minor details, but they all un- 

 doubtedly belong to a single species. A specimen from Atwood's shark 

 has been figured in general outline by Prof. S. I. Smith {loc. cit). 



Following is Say's description : 



"P. sinuatus. Body dilated, thorax eraarginate before, abdomen sin- 

 uate behind. 



"Inhabits dog fish {Squalis canis f Mitchell). Cabinet of the Acad- 

 emy [of Philadelphia]. Length, one-fifth of an inch. 



"Body longitudinally oblong quadrate; thorax transverse quadrate, 

 somewliat narrowed before, emarginate between the antenna^, middle 

 of the base rectilinear and fuscous, angles projected backwards and 

 rounded at tips ; antenn;^ very short ; anterior feet formed for suction, 

 at tip oval or subreniform, and placed obliquely ; scales, four subequal 

 ones in a transverse line at the base of the abdomen, each transverse 

 and rounded at tip, and two larger ones originating beneath the pre- 

 ceding, slightly dentate at tip, and not concealing half of the abdomen; 

 abdomen quadrate, as wide as the thorax but rather longer, posterior 

 edge with a central sinus and lateral one each side, posterior angles 

 acute; oviducts filiform. 



"Very commonly occur on this species of Squalis, attachiug them- 

 selves more particularly about the bases of the fins. They are by no 

 means so active as the Caligus piscinus, which also occurs in plenty, on 

 the codfish of our coast." 



The following description is drawn up mainly from specimens obtained 

 from the sand-shark, but the principal differences exhibited by speci- 

 mens from the dog-fish and Atwood's shark are also noted. 



310 



