Wotes on North American Crustacea. 245 



with very few spines sparsely scattered. Lengtli of the carapax, 0.28 ; 

 breadth, O.IG ; length of cheliped, 0.Y7 inch. 



It is the first species of the genus which has occurred upon 

 the American shores. No true Galathea is found in the waters 

 of the Kew World, notwithstanding the abundance of species 

 and individuals in tlie Old. 



Pleuroncodes, nov. gen. 



We propose this new genus for the reception of the Galathea 

 monodon of Milne Edwards, described in the " Histoire Natu- 

 relle des Crustac^s," vol. ii. p. 276, and figured in the " Annales 

 des Sciences Katurelles," Zool., t. xvi. pi. xi. f. 6. It is closely 

 allied to Munida in the characters of the front, etc., but the 

 sides or latero-inferior regions are greatly swollen, so that 

 the epimeral sutures are seen from above. The insertion 

 of the external antennae is also plainly seen from above, and 

 not concealed beneath the antero-lateral angle of the carapax 

 as in Munida. In the external maxillipeds the meros is un- 

 armed, and the penult joint is slightly dilated, though much 

 less so than in Grimothea. 



Pleuroncodes planipes, nov. sp. 



Yery close to P. monodon, but with the ambulatory feet longer and 

 more flattened than is represented in the figure of that species published 

 by Milne Edwards. The penult joint of the ambulatory feet in our 

 species is particularly flattened, and ciliated : — the upper surface is 

 smooth except at the raised, granulated margins, and a slight obtuse 

 median ridge. Length of carapax in a male, rostrum included, 0.95 ; 

 greatest breadth, 0.54 ; length of cheliped, 1.90 inch. 



It may prove identical with P. monodon. We have no 

 opportunity of comparing specimens. 



