4 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



a' '. Body narrow, produced, depressed. Mandibles with a three-jointed palp. 

 Superior or first pair of antennae with two multiarticulate flagella. Anterior 

 maxillae with two masticatory lobes and a two-jointed palp; posterior ones 

 well developed and setose. Second pair of legs with a large, broad, flat hand. 

 Epignath of maxillipeds large, laminar, branchial in character. 



Family II. APSEUDIDJE 



Family I. TANAID^. 



Body scarcely attenuated behind. First pair of antennae simple, 

 without any secondary filament or flagellum. Single flagellum some- 

 times absent, and generally rudimentary, rarely well developed in 

 female, and multiarticulate in male. Second antennae without a scale; 

 flagellum usuall3 T rudimentary, rarely well developed. Mandibles 

 without palp. Second maxillae represented by minute rudimentary 

 lobes. Anterior maxillae with only a single masticatory lobe. Epig- 

 nath of maxillipeds narrow, falciform. Second pair of legs not differ- 

 ing from the following peraeopods. Gnathopods never furnished with 

 palps or exopods. Pleopods with branches uniarticulate. Uropoda 

 simple or furnished with two short filaments. 



ANALYTICAL KEY TO THE GENERA OF TANAID.E. 



a. Less than five pairs of pleopoda present. Uropoda simple, short, single-branched. 



Eyes present. 

 b. Only two pairs of pleopoda present. Abdomen composed of three segments. 



Uropoda composed of only two articles Genus Pancolus Richardson 



b'. Only three pairs of pleopoda present. Abdomen composed of five to six seg- 

 ments. Uropoda composed of three to seven articles. 



Genus Tanais Audouin and Edwards 

 a'. Five pairs of pleopoda present. Uropoda double-branched. 



b. Incubatory pouch formed only by two lamellae issuing from bases of fourth pair 



of legs Genus Cryptocope Sars 



&'. Incubatory pouch normal, 

 c. Inner branch of uropoda 2-3 jointed. Pleopoda in female very small, or 



rudimentary Genus Leptognathia Sars 



(/. Inner branch of uropoda more than 2-3 jointed. Pleopoda well developed. 

 d. Gnathopods in male imperfectly chelate, without any finger, or with finger 



very short and immovable ". Genus Heterotanais Sars 



d' '. Gnathopods in male with chelae fully developed. 



e. Gnathopods in male very much elongated, with carpus attenuated, hand 

 very large, oblong, fingers elongate and curved ; immovable one strongly 

 tuberculate within. Thoracic appendages not specialized into an ante- 

 rior and a posterior series Genus Leplochelia Dana 



e / . Gnathopods in male with chelse very stout, the distal section of the 

 penultimate joint extremely broad, with a toothed margin. Thoracic 

 appendages specialized into an anterior and a posterior series. 



Genus Neotanais Beddard 



See Sars' Crust, of Norway, II, 1899, pp. 10, 11, and Norman and Stebbing, 

 Trans. Zool. Soc. London, 1886, XII, pp. 102-103, for characters given below. 





