624 



Bulletin American Museum of Natural History 



[Vol. XLVIII 



coat of pubescence. The carapace is very convex antero-posteriorly, 

 slightly convex from side to side. The antero-lateral margins are armed 

 with long spines, the orbit and the front with shorter spines. Chelipeds 

 spinous above and also on the outer surface of the palms except on the 

 lower portion of the larger palm. On the legs, the upper surface of the 

 carpus-propodus and the distal extremity of the merus are spined. 

 The differences are as follows: 



P. spinohirsutus 



Antero-lateral spines 5; the first or 

 orbital spine is a little shorter than the 

 others and the space between first and 

 second is less than the other spaces, the 

 bases of those spines often contiguous, 

 so that they appear like one deeply bifid 

 spine. 



No subhepatic spine, although there 

 may be some small spinules. 



Frontal spines short. 



In male usually half of outer surface of 

 larger hand is smooth and naked, the 

 smooth area separated obliquely from the 

 rough area by a line running from the 

 lower proximal corner to the distal end 

 opposite the middle of base of dactylus. 

 In female the smooth space is similar to, 

 but smaller than, that of the male. 



Carapace wider, width (exclusive of 

 spines) more than 1% times length. 



P. towwsendi 

 Antero-lateral spines 4, equally sep- 

 arated. 



A slender, well-marked, subhepatic 

 spine, below the interval between first 

 and second lateral spines. 



Frontal spines longer. 



In both sexes less than half of outer 

 surface of larger hand is smooth. A con- 

 tinuous line of short, conical spines runs 

 lengthwise in line with the base of cutting 

 edge of propodal finger. 



Carapace narrower, width (exclusive of 

 of spines) 1%, or less than 1%, times 

 length. 



P. spinohirsutus runs larger than the next species, measuring 23.4 

 mm. (Cat. No. 32964, U. S. N. M.) in total length of carapace as con- 

 trasted with 14.2 in townsendi (type). 



P. spinohirsutus shows a tendency to produce a posterior branch 

 on the third lateral spines. 



Pilumnus townsendi, 1 new species 

 Plate XXVIII 

 Pilumnus spinohirsutus Rathbun, not Lockington, 1904, 'Harriman Alaska Exped.,' 

 X, p. 185 (part), PI. vn, fig. 2; 1910, Proc. U. S. Nat. Mus., XXXVIII, p..585 

 (part). 



'For Dr. Charles H. Townsend, in charge of the 1911 expedition. 



