164 



First pair of limbs slender, carpus and raeros sub-equal, propodus 

 about two thirds the length of carpus, dactyli about equal to palmar 

 portion. 



Second pair greatly developed, equal to the body in the female, and 

 exceeding it in the male; propodus stout, dactyli one half as long as 

 the palmar portion, pollex with two large obtuse teeth on its inner 

 border, and a slightly hooked point, dactylus slender, with a large 

 sharp-pointed, triangular, compressed tooth in the middle of its length, 

 closely fitting between the teeth of the pollex. 



Dactyli of hinder four pairs bi-unguiculate. 



Three last segments of pleon compressed, a spine on each side of 

 the posterior border of the penultimate segment. 



Total length of a well-grown specimen from tip of rostrum to end 

 of abdomen, about 34 millims; length of manus of adult male, 17 

 millims ; ditto of a well-grown female 13 millims. 



The females are similar to the males, but the manus of the second 

 pair is somewhat shorter. 



Several specimens were taken from the interior of the shell of the 

 common Pinna, of the Gulf of California; localities: Angelas Bay, 

 Mulege Bay, San Jose Island. They were collected in the months of 

 July and August, at which date the females were loaded with eggs. 



From P. margarita S. I. Smith, this species may readily be distin- 

 guished by the much greater development of the manus of the second 

 pair. From M. Edwards' description of P. Ujrrhena (Hist. Nat. des 

 Crust., Vol. II, p. 361), which inhabits the Pinna of the Mediterra- 

 nean, this species differs in lacking the tooth upon the rostrum. 



Sicyonia penicillata n. s. 



Rostrum deep, shorter than peduncles of eyes, with four spines 

 above, one forming the tip, the next immediately above and slightly 

 posterior to it, the third midway between the second and fourth, 

 which is upon the carapax. Carina of rostrum extending backwards 

 the whole length of the carapax; developing a strong spine, directed 

 forwards, just anterior to the centre of the carapax, and a stronger 

 similar spine near its posterior border. 



Central carina higher behind the former of these spines, curving 

 upwards to the posterior spine, then downwards till it disappears on 

 the posterior border of the carapax. 



Spines of rostrum preceded by a few hairs, the central spine of car- 

 apax by quite a mane of hairs, and. the posterior spine with a similar 

 mane. 



A spine on the exterior orbital margin, and a second posterior to it, 

 on the hepatic region. 



