ABT. 5. NORTH AMERICAN PARASITIC COPEPODS WILSON. 23 



Genus ANTHOSOMA Leach. 



Caligus (part) Abildgaard, 1794. See under Anthosoma crassum. 



Generic characters of female. — General body form short and 

 rather stout. Cephalothorax covered with an ovid carapace more 

 than half the entire length of the body. Genital segment and 

 abdomen entirely covered dorsally by two large elytra, which overlap 

 considerably along the midline; also, entirely concealed ventrally 

 by three pairs of overlapping foliaceous swimming legs. Abdomen 

 small and one-jointed. Egg strings narrow and three times the body 

 length. First antennae slender, six-jointed; second antennae stout, 

 jointed, terminating in a strong claw; maxillipeds short and very 

 strong, with a powerful terminal claw. 



Generic characters of male. — General body form and appendages 

 very similar to those of the female, but the genital segment and 

 abdomen have no dorsal elytra and so are visible in dorsal view. 

 The first two pairs of foliaceous swimming legs have one-jointed 

 rami in the notches on the inner margins. 



Type of the genus. — Anthosoma crassum (Abildgaard), mono- 

 typic. 



Remarks. — This genus has but the single species and it is easily 

 recognized by the dorsal elytra and the foliaceous swimming legs, 

 since they are quite different from anything found in other genera. 

 In spite of the fact that the genus is so old and so well known there 

 are still some details of structure which have never been presented. 



ANTHOSOMA CRASSUM (Abildgaard). 



Plate 1, figs. 1-8. 



Caligus crassus Abildgaabd, Skrivter af naturhistorie Selskabet, Kj0ben- 



havn, vol. 3, 1794, p. 46, pi. 5, figs. 1-3. 

 Caligus imhricatus Risso, Histoire naturelle des Crustac6s des environs de 



Nice, 1816, p. 162, pi. 3, fig. 13. 

 Anthosoma smithii Leach, Supplement to 4th, 5th, and 6th ed. Encyclopedia 



Britannica, vol. 1, 1816, p. 406, pi. 20, figs. 1-6. 

 Otrophesia imbricata Risso, Histoire naturelle des principales de I'Europe 



m^ridionale, vol. 5, 1826, p. 136. 

 Anthosoma crassum, Gould, A Report on the Invertebrata of Massachiisetts, 



1841, p. 340. 

 Anthosoma crassura Steenstrup and LiItken, Kougel. Danske Vidensk. 



Selsk. Skrifter, ser. 5, vol. 5, 1861, p. 397, pi. 12, fig. 24. 

 Anthosoma crassum T. and A. Scott, British Parasitic Copepoda, 1913, p. 



108, pi. 23, figs. 5-6. 



Host and record of specimens. — A single female from the gills of 

 the sand shark, Carcharias littoralis, at Woods Hole has received 

 Cat. No. 6039, U.S.N.M. Another female from the gills of the por- 

 beagle shark, Lamna comuhica, probably from Woods Hole, bears 

 Cat. No. 8108 U.S.N.M. A finely preserved male from the mouth of 



