204 THE VOYAGE OF H.M.S. CHALLENGER. 



four teeth ou the upper margin, of which the second is the most conspicuous ; the lower 

 divides into two, each being armed with a few conspicuous teeth. 



The second and third pairs are slender and chelate and armed on the upper oY outer 

 margin of the meros with three or four sharp teeth. 



The fourth and fifth pairs are subchelate and have two sharp teeth on the anterior 

 part of the upper margin of the meros, and two or three on the lower. They have the 

 propodos roughened on the outer side by numerous anteriorly-directed tubercles, the 

 summits of which are crowned with a fasciculus of stiff hairs ; that on the inferior distal 

 extremity of the posterior pair is also armed with a small tooth and forms a rudi- 

 mentary pollex ; the dactylos in each is much longer than the poll ex and narrower than 

 the propodos. 



The posterior pair of pleopoda, forming the lateral plates of the rhipidura has a distinct 

 smooth ridge down the middle of the inner and outer plates. On the outer it is produced 

 to the posterior margin, passing through the minutely serrate diseresis ; on the inner 

 it terminates in a sharp tooth within the margin. 



Observations. — The specimen from which I have drawn the description is a female, 

 apparently of mature growth, being nearly 4 inches in length. It has the vulva closed 

 by a calcified operculum. In general aspect it more nearly resembles the specimens of 

 Astacopsis franklinii of Gray than any others ; but differs from them in several details, 

 among which the most conspicuous are the absence of a strong cusp or tooth from the 

 centre of the pollex of the first pair of pereiopoda, the presence of conspicuous teeth 

 on the first antennal region of the carapace, the large tubercles on the branchial 

 region, and the absence of five or six sharp teeth on the lateral walls or coxal plates of the 

 second somite of the pleon. 



Astacopsis sy.dncyensis, n. sp. (PI. XXVII. fig. 2). 



Carapace smooth with microscopically small punctations and hairs. Eostrum having 

 three small teeth on each side. Two teeth, one before the other, on each side behind 

 the orbit. Pleon smooth. Telson slightly dentate and corrugated. 



First pair of pereiopoda slightly unequal, surface smooth, margins slightly roughened. 

 Carpos with one tooth on the inner and one on the upper margin ; meros with three on 

 the upper and three on the lower margin. 



Length (female), 50 mm. (2 in.). 



Habitat. — Sydney, Australia. One specimen. 



The carapace is smooth and minutely punctate over the entire dorsal surface, 

 laterally sparsely covered with microscopically small hairs, which on the branchial region 

 exist in small fasciculi. The rostrum tapers to a sharp point, and the sides are 



