166 MR. GEOFFREY SMITH ON THE 



keels ; it ends in a sharp spine, with two lateral serrations on 

 each side. 



The lateral keel on the carapace is prominent and arched 

 outwards ; anteriorly it does not terminate in a prominent spine. 

 There is a well-marked median keel. 



There is no prominence on the carapace behind the postorbital 

 spines, nor are there any tubercles upon the carapace, branchio- 

 stegites, or abdomen ; nor are there any bunches of hairs. 



The first maxilla has the terminal segment or flagellum of the 

 endopodite entirely repressed (PI. XXYII. fig. 29). 



The third maxillipede has its inner borders abundantly clothed 

 with hair. 



On the telson there are two lateral spines, but no medio- 

 lateral ones. 



The great cheliped is long, but not slender ; the carpus is very 

 long, but stout ; the dactylopodite is only about one-third as long 

 as the carpus. The pincer is slightly tuberculated internally and 

 there is a carpet of fine hairs upon the inner margin of the carpus. 

 There is a row of small tubercles upon the upper ridge of the 

 ischiopodite. 



Greatest length 4| inches. 



Locality. — Western Australia, in streams tributary to the 

 Swan River. 



CHiERAPS TENUIMANUS, Sp. n. (Pls. XXII. & XXVII. fig. 30.)- 



The rostrum is deeply excavated in the middle, with sharply 

 upstanding lateral keels. The rostrum ends in a sharp spine, and 

 there are three lateral serrations on each side. 



The lateral keel on the carapace is prominent and arched 

 oiitwards, ending anteriorly in a prominent spine. The median 

 keel is also much pronounced. 



There is a distinct prominence on the carapace running back 

 from the postorbital spine, on which a few small tubercles are 

 situated. There are also a few small tubercles on the branchio- 

 stegites, and the body is covered with numerous groups of shoit 

 inconspicuous hairs. 



The first maxilla has the endopodite consisting of a broad basal 

 segment, with the flagellum represented by a small conical segment, 

 the base of which is much smaller than the top of the segment 

 with which it articulates (PI. XXVII. fig. 30). 



The third maxillipede is only sparsely provided with hairs. 



On the telson, besides the two lateral spines at the junction of 

 the calcified and membranous portions, there are two median 

 spines. 



The great cheliped is fairly long a,nd very slender. The carpus 

 is long and slender ; the dactylopodite is more than half as long- 

 as the hand. There are no enlarged tubercles on the pincer and 

 there is no cai-pet of fine hairs on the inner margin of the carpus. 

 The row of tubercles on the upper i-idge of the ischiopodite is 

 retluced to one or two small tubercles. 



