486 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



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



o. Head of moderate size, deeply emarginate on each side for the insertion of the 

 antenme, frontal part produced. First four thoracic segments transversely 

 excavated dorsally. First pair of antennse with flagellum multiarticulate. Nata- 

 tory legs of the same structure, carpal joint foliaceous. 



6. Body with anterior division much broader than posterior; three posterior seg- 

 ments densely crowded together. Mandibles without any molar expansion; 

 cutting edge but slightly dentated. First two pairs of legs of same structure, 

 though somewhat different in size; two succeeding pairs elongated. Dactylus 

 wanting on natatory legs. Uropoda simple, biarticulate. 



Genus Munnopsis M. Sars 



V . Body with anterior division less sharply marked off from posterior; three 

 posterior segments very large and broad. Mandibles with molar expansion ; s 

 cutting edge divided into strong teeth. First pairs of legs shorter than three 

 succeeding pairs, which are subequal and very much elongated. Dactylus 

 distinct on natatory legs. Uropoda biramous, branches single jointed. 



Genus JEurycope G. O. Sars 



a'. Head very large and broad, transversely truncated in front, lateral parts greatly 

 expanded. First four thoracic segments slightly excavated transversely. 

 First pair of antennae with flagellum not much elongated. First two pairs of 

 natatory legs of similar structure, carpal joint large and expanded, cordiform; 

 last pair much narrower than two preceding pairs, carpal joint but slightly 

 expanded. Caudal segment triangular in form... Genus Ilyarathna G. O. Sars 



78. Genus MUNNOPSIS M. Sars. 



Anterior division of body broader than posterior division. Head 

 moderately large, deeply emarginate on either side of a narrow 

 frontal process. First pair of antennae with a multiarticulate flagel- 

 lum, longer in male than in female. Second pair of antennae with the 

 last two articles of the peduncle greatly elongated. Mandibles without 

 molar expansion; cutting edge but slightly dentated. 



First four segments of thorax transversely excavated dorsally ; the 

 three last segments crowded together and very convex. 



Terminal segment of body large, oblong-ovate. 



First two pairs of legs of similar structure, but differing in size; 

 two following pairs exceedingly long and slender; natatory legs of 

 similar structure, carpus and propodus expanded, dactylus wanting. 

 Uropoda simple, biarticulate. 



MUNNOPSIS TYPICA M. Sars. 



Munnopsis typica M. SARS, Chr. Vid. Selsk. Forh., 1860, p. 84, 1861. G. 0. SARS, 

 Chr. Vid. Selsk. Forh., 1863, p. 206, 1864; Nyt. Magazin for Naturvidenska- 

 berne, 1866, p. 5. M. SARS, Christ. Fjord Fauna, 1868, p. 70, pis. vi, vn, figs. 

 101-138; Chr. Vid. Selsk. Forh., 1868, p. 261, 1869. G. O. SARS, Nyt. Magazin 

 for Naturvidenskaberne, 1869, p. 44; Chr. Vid. Selsk. Forh., 1872, p. 79, 

 1873. BUCHHOLZ, Zweite Deutsche Nordpolfahrt, Crust, 1874, p. 285. 

 HKLLER, Denksch. Acad. Wiss. Wien, XXXV, 1878, p. (14) 38. NORMAN, 

 Proc. Royal Soc., XXV, 1876, p. 208. G. O. SARS, Arch. Math. Nat., II, 



See Sars for characters of genus, Crust, of Norway, II, 1899, p. 132. 



