FRESinvATER CRAYFISHES OF AUSTRALIA. 1 09 



keels upon it. It eiuls in a spine and there are two inconspicuous 

 lateral serrations on each side. It closely resembles the rostrum 

 of Parachoiraps bicarinatus. 



The lateral keels on the carapace are blunt and deepened, 

 ending posteriorly in a rounded boss. There ai-e no other 

 tul)ercles, prominences, or groups of hairs upon the body. So far 

 the external features are practically identical with P. bicarinatus, 

 but it can be at once distinguished by the generic character of 

 the length between tip of rostrum and cervical suture being 

 greater than that between cervical suture and end of carapace. 



The first maxilla has a very small pointed terminal segment on 

 the endoj)odite, which articulates by a broad base on to the basal 

 segment (PI. XXYII. fig. 34). 



The third maxillipede is fairly well provided with hairs on its 

 inner borders. 



There are no median spines on telson. 



The great cheliped is stout and broad ; the hand itself being 

 broad and rather flattened ; the dactylopodite is about equal in 

 length to the inner border of the carpus. The finger is definitely 

 tuberculated internally, often with two enlarged tubercles. There 

 is a small carpet of fine hflirs on the inner margin of the carpus. 

 On the under side the carpus has a pronounced longitudinal 

 ridge with marked excavations on either side of it. 



The upper ridge of the ischiopodite has a row of small round 

 tubercles upon it. 



Length 4 inches. 



Localit)/. — Two specimens from Westetn Australia, April 30th, 

 1880. No further locality given. 



Remarks on the above sjKcics. — This species is of considerable 

 interest, as it foi'ms a transition from the genus Ghairaps to 

 Parachifraps bicarinatus-. In generftl appearance, in the features 

 of the claws, carapace, rostt-um, etc., it agrees exactly with 

 Paracluvraps ; in the fact that the posterior arthrobi-anch is not 

 rudimentary, the stertial keel is sharp ai\d very prominent, the 

 interantennal spine is pointed and not rounded, the antennal 

 scale is not conspicuously bi'oad, and in the length between tip 

 of rostrum and cervical suture being gi-eater than between latter 

 and end of carapace, it exhibits the characteristic features of 

 the genus Chteraps. 



List of LiteratuJie. 



1. 8HAWi— Zoology of Kew Holland, Vol. i., 1H43. 



2. Oray. — Eyre's Journals of Expeditions of Discovery into 



Central Australia, Vol. i., 1845. 



3. Erichson. — Archiv fiir Naturgeschichte, Jahrg. 12, 1846. 



4. Dana. — United States Exploring Expedition : Crustacea. 



Part I., 1852. 

 b. iVCiLNE-EmvAUDS. — Hist; Nat. Crust;, Vol. iii p. 332; 



