164 
First pair of limbs slender, carpus and meros 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 José Island. ‘They were collected in the months of 
July and August, at which date the females were loaded with eggs. 
From P. margarita S. 1. 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. tyrrhena (Hist. Nat. des 
Crust., Vol. Il, p. 361), which inhabits the Pinna of the Mediterra- 
nean, this species differs in lacking the tooth upon the rostrum. 
Sicyonia penicillata n. s. 
Zostrum 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, 
