498 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



Family XX. BOPYRID^. 



Body of female distinctly segmented and somewhat asymmetrical* 



Both pairs of antenna? rudimentary. Maxillipeds composed of two 

 articles, and very frequently with a small terminal article, the palp; 

 two curved lanceolate appendages at the base represent the epignaths. 



Coxal plates usually denned. 



There are five pairs of incubatory lamellae; the first pair is composed 

 of two segments. 



Abdomen more or less distincth T defined. Pleopoda simple, bira- 

 mous, or triramous; sometimes obsolete. Uropoda, when present, 

 simple, lanceolate. 



Legs usually in seven pairs, sometimes absent on one side with the 

 exception of the first; all are similar in structure, short, prehensile. 



Male symmetrical. Head rounded in front. All seven segments of 

 thorax distinct. Segments of abdomen sometimes distinct, sometimes 

 united. Legs similar in structure, all prehensile. 



Parasitic on decapods. 



ANALYTICAL KEY TO THE GENERA OF THE FAMILY BOPYRID.E. 



a. Body of female with one side greatly swollen and much longer than other side. 

 Abdomen composed of only five segments. Only first leg present on larger 

 side; others absent. Coxal plates only visible on shorter side. Marsupial 

 plates largely developed on longer side of body, and inclosing the entire 

 incubatory cavity; incubatory lamellae of shorter side small. 



Genus Phryxus Rathke 

 a' '. Body of female with neither side swollen. Abdomen usually composed of six 



segments. All the legs of both sides present. 



b. Abdomen of female with the lateral parts or pleural lamella? elongated, digitate. 



c. All six segments of the abdomen with the pleural parts elongated, digitate. 



Male with the lateral parts of the segments of the abdomen or pleural 



lamellae elongate Genus lone Latreille 



c' '. Only the five anterior segments of the abdomen with the pleural parts 

 elongated, digitate. Male with the lateral parts of the segments of the 

 abdomen not elongate. 



d. Female without median dorsal tubercles on sixth and seventh segments of 

 thorax. Exopods present on all seven pairs of legs. Uropoda of male 



filiform Genus Leidya Cornalia and Panceri 



d' . Female with median dorsal tubercle on sixth and seventh thoracic seg- 

 ments. Exopods not developed on any of legs. Uropoda of male rep- 

 resented by two bunches of stiff hairs. 



Genus Crapsicepon Giard and Bonnier 

 b'. Abdomen of female with the lateral parts or pleural lamellae not elongated 



or digitate. 



c. Lateral parts or pleural lamellae of abdomen of female produced lamellarly. 

 d. Uropoda in female double-branched. Abdomen in male with segments 



fused Genus Munidiou Hansen 



d' '. Uropoda in female single-branched. Abdomen in male with segments 

 distinct. 



See Sars for characters of genus, Crust, of Norway, II, 1899, pp. 195-196. 



