106 MESSES. NOEMAN AND STEBBING ON THE 



iSynojiS'is of Genera of Tanaiclae. 



A. Pleon not segmented, tlie first five segments coalesced. No pleo- 



pods. Uroi)ods imperfectly biramose, external branch a conical 

 process, inner 2-jointed, half as long as pleon. No eyes. Tipper 

 antennae 4-jointed. Gnathopods with the basal portion of 

 unusual form, composed of two distinct segments, oblong, tumid; 

 hand small and weak Anarthrura, G. O. Sar.s. 



B. Pleon segmented, but no pleopods. 



{a) Uropods imperfectly biramous, external branch tubcrculiform, 

 inner 2-jointed, minute. No eyes. Upper antennae 4- 

 jointed. Gnathopods of usual form. Hinder perseopods 

 with basal joint constricted in its upper portion .... Strongylura, G. O. Sars. 



[b) Uropods consisting of a single branch, a basal joint constituting 



the peduncle, and a second conical joint representing the 

 branch. No eyes. Upper antennae 4-jointed. Gnathopods 

 strong, of the usual form. Perseopods slender, with a long 

 finger terminating in a long nail ; the anterior pairs more 

 spined than the posterior, the latter not having the basal 

 joint constricted above Tanaella, n. g. 



(c) See Pseudotanais and Leptognnthia, further on. 



C. Pleon segmented ; pleopods only three pairs, which are densely 



setose. Uropods short, simple, the single branch composed of 

 2-3 joints. Eyes. Upper antennae 3-jointed, with rudimentary 

 flagellum. Hinder perseopods with a curved, hamate, strong 

 finger Tanais, Aud. & M.-Edw. 



D. Pleon segmented ; pleopods all developed, but rudimentary, and not 



setose in female. No eyes. 

 («) Uropods very short, branched, inner 2- ( ? ), 3- (c?) jointed, 



outer 1- ( $ ), 3- ( (J ) jointed. Segments of perajon divided 



by deep instrictions. Gnathopods alike in the sexes, of usual 



form. PerjEopods with a long finger. " Mandibulae bene 



evolutae, acie serrulata, lamella secundaria m. dextrae valde 



exstante, processu molari sublaminari, inermi " .... Cryptocope, G. O. Sa,rs. 

 (b) Uropods moderately long, with unequal 2-jointed branches. 



Gnathopods not strong, of the usual form. Peraeopods, 



hinder pairs with long finger. " Mandibulae bene evolutae, 



corpore sat elongato, processu molari cylindrico, apice 



truncato et denticulis acutis cincto " Haplocope, G. O. Sura. 



E. Pleon segmented. Pleopods all developed and ciliated. No eye- 



lobes or eyes. 

 (a) Pleopods developed and ciliated, or altogether absent in female. 

 No ocular lobes ; eyes present or absent. Upper antennae 

 3-jointed, nearly alike in sexes. Gnathopods alike in 



