40G PROCEEDINGS OF THE ACADEMY OF [1879. 



Petrolisthes armatus Stm. 



Porccllana armata Gibbes, Proc. Am. Assoc, iii. p. 90; Proc. Elliot 



Soc'y, i. f. 11, pi. i. f. 4 ; Martens' Wieg. Arch., xxxviii. p. 121, pi. 



v. f. 11. 

 Petrolisthes armatus Stm., Proc. Phila. Acad., 1858, p. 227,' vii. p. 73. 



Specimens were collected at Sarasota, Charlotte, and Florida 

 Bays. Other localities are Key West! (Packard), Florida (Gibbes), 

 Aspinwall, St. Thomas, and Panama (Stm.), Cuba (Martens), 

 Fonseca, west coast Nicaragua! (McNiel), Gulf of California 

 (Lockington). 



Dr. von Martens quotes P. galathina Bosc as a synonym of this 

 species, which is surely erroneous. 



Genus PISOSOMA Stm. 

 Pisosoma glabra, sp. n. Plate xiv. fig. 2. 



Carapax convex, a little broader than long, polished, microsco- 

 pically punctate. Front advanced, broad, three lobed, the median 

 lobe being slightly more advanced than the lateral ones. Anten- 

 nae about twice as long as the carapax, the basal joints similar to 

 those of Petrolisthes. Chelipeds short, stout; rneros subcubical, 

 its anterior margin distally armed with an acute tooth directed 

 toward the carpus ; carpus stout, broader than long, its anterior 

 margin expanded, with a strong tooth on the proximal portion, 

 the remainder with rounded teeth, the posterior portion of the 

 upper surface is roughened, and the posterior margin distally 

 armed with minute rounded teeth. Hand twice as long as broad, 

 microscopically granulate, a shallow sulcus on the posterior por- 

 tion of the palm producing a cristate appearance of the posterior 

 margin ; fingers not so long as palm, completely closing, the dac- 

 tylus with a shallow groove above. Beneath, the chelipeds are 

 smooth and polished. Ambulatory feet sub-cylindrical, hairy 

 above. This species differs from Stimpson's description of his 

 imperfect specimen of P. riisei in the simple, not bimarginate 

 character of the front, etc. 



Five specimens were collected at Key West. 



Length of carapax 4.1 mm., breadth 4.5 mm., ratio 100 : 110. 



Genus PORCELLANA Lamarck, Stimpson. 

 Porcellana pilosa Edw. 



Porcellana pilosa Edw., Hist. Crust., ii. p. 255. 

 Carapax longitudinally convex, surface even, and covered with 



