Abchet. — Fresh-water Crayfish of New Zealand. 



305 



IV. Rostrum (columns 3, 4, and 5). 



The rostrum is shorter in proportion to the body length than in P. plani- 

 fruits, and it is also shorter in proportion to its own width. Specimens 

 from Rangiora and Peel Forest have a rostrum still shorter than is usual for 

 the species. There is also a distinct median keel on the anterior portion of 

 the upper surface of the rostrum ; it is not so distinct in the Peel Forest 

 specimens. There are usually 4 sharp distinct spines on each side of the 

 rostrum, and 1 or 2 below. 



V. A ate una} Scale (columns 6 and 7 ; fig. 8). 



The antennal scale is fairly long and narrow, though not so long as in 

 P. plan if i oiis ; it is nearly as long as the peduncle of the antenna ; it tapers 

 from the posterior third. 



Fig.- 8. — Antemial scale of P. setosus: X3. 



VI. Chelae (fig. 9). 



The upper surface of the ischium is slightly serrated in moderate-sized 

 individuals, but large specimens have distinct, forwardly directed teeth ; 

 on the lower surface are 2 sharp spines, with 1 or 2 small tubercles between 

 them in large specimens. 



On the posterior portion of the upper margin of the merus is a single 

 row of spines leading forward on the anterior part to 2 rows ; there are 

 2 irregular rows on the lower margin, and on each side of th.e anterior 

 margin is a single forwardly directed spine. 



The inner surface of the carpus has usually 3 large spines ; the upper 

 surface has 2 irregular rows of small spines, separated by a shallow groove ; 

 there are small tubercles on the outer surface, and 3 or 4 large sharp spines 

 on the lower surface. 



On the inner margin of the propod there is a row of sharp spines, con- 

 tinued, with smaller spines, along the corresponding edge of the dactyl. 

 Above this row there is, on the dactyl, another row of smaller spines, com- 

 mencing usually with 1 spine on the anterior portion of the propod. The 

 outer edge of the propod has 2 rows of close-set, short spines. On the pos- 



