ISOPODS OF NORTH AMERICA. ' 63 



ANALYTK'AI- KKY To THE GKXKKA OF TIIK FAMII.V ANTUrUID.K « 



a. Labium teniiinatiug in two rounded lobes. Mandibles with cutting edge eom- 

 posed of two or three ))lunt teeth. First niaxilke simple, terminating in con- 

 spicuous and well-developed teeth. Maxillipeds with palp com2)osed of one to 

 four articles. 

 h. First five segments of alxhjmen coalest-ed into a single segment in tlie female. 

 I\Iaxillii)e(ls with palp comj)Osed of two articles. Flagella of both pairs of 

 antenna' rudimentary in l)oth sexes. Flagellum of first pair not greatly devel- 

 oped in male Genus Cyathura Norman and Stebbing 



I/. Segments of abdomen distinct in the female. 



c. Maxillipeds M'ith the palp composed of a single article. Flagella of both i>airs 

 of antennt¥ in the female composed of oidy a few articles. In the male the 

 first pair has a multi-articulate fiagellum. Mandible with a one-jointed 



jialp Genus Plilanthum I larger 



("'. Maxillipeds with a palp composed of four articles. Flagella of both pairs 

 of antenna' multi-articulate; that of lirst pair in the male developed into a 

 remarkable brush-like organ. Mandible with a three-jointed palp. 



Genus Anthelura Norman and Stebbing 

 a^. La])ium terminating in two points, acuminate. Mandil)les without teeth, ter- 

 minating in an acutely pointed lancet-like organ. First maxillaj simple, spear- 

 like, terminal part armed with recurved teeth. Maxillipeds with basal part 

 narrows olilong; i)a]p composed of three articles. Segments of abdomen dis- 

 tinct in female. 

 b. All seven pairs of legs present in adult. Seventh thoracic segment normal, 

 well developed. 

 c. Both pairs of antenna' in both sexes with multi-articulate fiagella. 



Genus Calathura Norman and Stebbing 

 c'. First pair of antennpe in both sexes have the flagellum multi-articulate. 

 Second pair of antennae in both sexes have a rudimentary flagellum com- 

 posed of a single article Genus Pantiithnra Bate and Westwood 



b^. Seventh pair of legs absent in adult. Seventh thoracic segment very short, 

 abruptly narrower than preceding sixth segment and not as wide as the 

 abdominal segments. First pair of antenna^ composed of four articles, the 

 last article being tlie rudimentary flagellum. Second pair of antenna com- 

 posed of five articles Genus Colanthura Richardson 



IS. Genus CYATHURA Norman and Stebbing. 'J 



First live seo-ineiits of abdomen coalesced into a single segment in 

 the female. Flagella of ]x)th pairs of antennae rudimentary. Maxilli- 

 peds with a palp composed of two articles. Mouth parts otherwise as 

 in Ptilanthura and Anthelura. 



CYATHURA CARINATA (Kr^yer).'" 



? Anthura gracilis De Kay, Zool. New York, Crust., 1844, p. 44, pi. ix, fig. 34. 

 Anthura carinata Kk0yer, Naturh. Tidsskr. (2), II, 1846-49, p. 402; Voy. en 

 Scand., 1849, pi. xxvii, fig. 3. 



« Norman and Stebbing's key has been used with slight modifications. See Trans. 

 Zool. Soc. Lond., XII, 188(), Ft. 4, pp. 121-122. 



''See Norman and Stebl>ing, Trans. Zool. Soc, Lond., XII, 1886, Ft. 4, p. 121, for 

 characters of genus. 



'"Norman and Stebbing give an excellent descrii)tion of this form. 



