ISOPODA OP THE 'LIGHTNING' AND OTHER EXPEDITIONS. 107 



sexes ; hand elongated^ fingers narrow and acuminate. 



First peraeopods with very long setiform finger. Hinder 



peraeopods with penultimate joint expanded, and furnished 



with a knife-like spine, finger short. Uropods biramous, 



branches 2-jointed. Marsupial pouch formed of only two 



lobes Pseudutanais, G. O. Sars. 



{b) Upper antennae with three articulations in female; in male 



much larger, with a 4-jointed flagellum. Gnathopods 



nearly alike in both sexes, not very strong ; hand narrow, 



fingers simple. First perajopods with a setiform finger; 



the hinder pairs short, with their basal joints very tumid. 



Uropods branched, each branch 1-2-jointed. Marsupial 



pouch of ustial character, composed of eight laminae . . Typlilotanais, G. O. Sars. 

 (c) Upper antennas in female 4-jointed, in male much larger; fla- 

 gellum 4-jointed, with large fascicles of sensitive cilia. 



Gnathopods in female moderately strong, hand dilated, 



fingers strong, the thumb serrulated ; in male more slender, 



with simple fingers. Perjeopods little differing from each 



other, more or less spinous. Pleopods sometimes not 



developed in female. Uropods 2-branched, inner 2- ( $ ), 



3- (c?) jointed; outer 1-2-jointed, or sometimes a mere 



tubercle Leptoynathia, G. 0. Sars. 



F. Pleon segmented. Pleopods . all developed and ciliated. Ocular 

 lobes and eyes present. 

 {a) Upper antennae in both sexes with a well-developed flagellum 



of about four joints, the flagellum in male with fascicles of 



sensitive cilia. Gnathopods of usual form in female ; finger 



and thmnb strong, the latter with tuberculated palm ; in 



male largely developed, oblong, finger and thumb curved, 



forcipiform, both strongly toothed within. Peraeopods 



much spined, the spines very variable in structm-e. Uro- 

 pods 2-branched, inner multiarticulate (8-9-jointed) ; outer 



2-jointed. No eyes Alaotanais, n g. 



(6) Upper antennae 3-jointed in female, 6-jointed in male, and 



furnished with bundles of sensitive cilia. Gnathopods not 



very dissimilar- in the sexes ; hand oblong, fingers short. 



Peraeopods of first pair slightly differing from the rest, with 



a long setiform finger; hinder pairs with first joint 



rather swollen. Uropods with two subequal 2-jointed 



branches Paratanais, Dana. 



(c) Upper antennae with three joints and rudimentary flagellum 



in female ; narrow and elongated, with a more or less 



developed flagellum in male. Gnathopods in female of the 



usual structure ; but in the male imperfectly chelate, 



without any finger, or the finger very short and immovable. 



