CBUSTACEA. 277 



slender penultimate joint of the first to third ambulatory legs ; the 

 short, curved dactyli are armed on their lower margins with a strong 

 accessory claw, posterior to which are one or two more small teeth. 

 Colour (in spirit) yellowish. Length of carapace about 2| lines 

 (5| millim.), breadth nearly 2 lines (4 raillim.). 



This species is scarcely distinguished from the typical Porcellana 

 latifrons, Stimpson, except by the somewhat different denticulation of 

 the lobes of the front, and in the latter having, as it -would seem, the 

 posterior margin of the wrist armed, as well as the anterior, with three 

 spines. The specimens described by Stimpson were from Hong Kong; 

 Porcellana armata, Dana, has a much less prominent front. 



Porcellana streptochirus of White*, from the Philippines, is, I 

 think, a mere variety of this species. It differs only in the somewhat 

 broader carapace, in having the frontal lobes armed with more nume- 

 rous spinules, and in having the under surface of the merus of the 

 chelipedes armed with three or four spines in place of the single 

 spine in P. quadrilobata ; and these characters are possibly due to 

 the greater age of the specimens. 



In one of White's specimens the wrist is tridentate, in the other it 

 is subentire. 



This species, in its elongated carapace and slender chelipedes, 

 establishes a transition to the genus (or subgenus) Porcellanella, the 

 species of which have a prominent and tridentate front. The genera 

 of the Porcellanidea stand much in need of revision ; and I may add 

 that I doubt the constancy of the characters derived by Stimpson 

 from the size and number of the denticulations of the dactyli of the 

 ambulatory legs as generic distinctions. 



There are in the collection three small specimens from Thursday 

 Island, 4-5 fms. (No. 165), which in many of their characters are 

 closely allied to P. serratifrons, Stimpson, yet are probably distinct, 

 but to which, on account of their very imperfect condition, I will 

 not apply a specific designation. In one specimen the chelipede is 

 probably aborted, having the palm narrow and twisted and the 

 fingers abnormally developed. These specimens are further distin- 

 guished from P. serratifrons by having three (not 1 or 2) spinules on 

 the sides of the branchial regions, six to eight spines on the anterior, 

 and two on the posterior margin of the carpus of the chelipede, &o. 

 In the single specimen (a young one) possessing both chelipedes the 

 lower margins of both right and left palms are spinulose. 



21. Galathea australiensis, Stimpson. (Plate XXXI. fig. A.) 



Here are referred a male from Port Denison, 4 fms. (No. Ill), 

 and another from Port Molle, 14 fms. (No. 93), in the first collec- 

 tion ; also a series of seven specimens from the Arafura Sea, 32-36 fms. 

 (No. 160), in the second collection, among which are both males and 

 females. Stimpson's description was from a female. In the adult 

 males I have examined the palms are broader and the fingers have 

 between them a hiatus when closed, and are strongly toothed on their 

 * List Crust. Brit. Mus. p. 64 (1847), deseript. nvlld. 



