ISOPODA OP THE ' LIGHTNING ' AND OTHER EXPEDITIONS. 107 



sexes; hand elongated, fingers narrow and acuminate. 

 First peraeopods Tvitli very long setifonn 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 



l°^ss Pseudotanais, G. O. Sars. 



(*) Upper antennae with three articulations in female; in male 



much larger, ivith a 4-jointed flagellum. Gnathopods 



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



fingers simple. First perjeopods with a setiform finger; 



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



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



pouch of usual character, composed of eight laminaj . . TypMotanuis, G. O. Savs. 

 (c) Upper antennre 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. Pera?opods little diflering from each 



other, more or less spinous. Pleopods sometimes not 



developed in female. Uropods 2-brauched, inner 2- ( ? ), 



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



tubercle Leptoynathia, G. O. Sars. 



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

 lobes and eyes present. 

 (a) Upper antenna in both sexes with a well-developed flagellum 



of about fom- joints, the flagellum in male with fascicles of 



sensitive cilia. Gnathopods of usual form in female ; finger 



and thumb strong, the latter with tuberculated palm ; in 



male largely developed, oblong, finger and thumb curved, 



forcipiform, both strongly toothed fl-ithin. Persopods 

 much spLned, the spines very variable in structure. Uro- 

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



2-jointed. No eyes Alaotanais, n g. 



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

 furnished with bundles of sensitive ciUa. Gnathopods not 

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

 Peraeopods of first pair slightly difi'ering 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 antenna 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 sti-ucture ; but in the male imperfectly chelate, 

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



