216 Ifotes on North American Crustacea. 



Piliminus lunatiis. 



Pilumnus lunatus M. Edw. et Lucas ; Voy. dans I'Am. Merid. 

 (D'Orbigny) Crust. 20, pi. ix. f. 2. 



Distinguished by its thickened, naked, anterior margins, and 

 by the peculiar sliarp hinated process on the superior margin 

 of the carpus joint of the ambulatory feet. It has no ridge 

 upon the palate, and should probably, with the preceding 

 species, be separated generically from Pilumnus. 



Found at Cape St. Lucas by Mr. Xantus, and on the west 

 coast of Central America by Capt. Dow. 



IWCetopocarciniis,* nov. gen. 



Carapax laevis, glaber, orbiculatus, antice truncatus ; regionibus non 

 circumscriptis ; margine antero-laterali fere integro, quam postero-late- 

 ralis breviore, pauUo cristato, crista postice introrsum curvata, ut in Pilum- 

 noide. Frons grandis, perlata, dimidiam carapacis lat. fere superans, 

 prominens, margine recta, integra. Orbita parva, margine superne 

 inteo-ra, subtus unifissa. Antenna externa hiatum internum orbitae 

 occupans, articulo basali frontem non attingente. Maxillipedes externi 

 eis Xanthus, etc. similes. Pedes mediocres. Abdominis maris seg- 

 menta tertium, quartum quinturaque coalita. 



ITIetopocarciniis trtincatus, nov. sp. 



PI. v., fig. 4. 



Carapax somewhat convex, naked, smooth and even, except that the 

 anterior gastric lobules and two oblong longitudinal lobules on the frontal 

 region are slightly raised. Antero-lateral margin obscurely three- or 

 four -toothed ; teeth to be seen only in a side view. Distance between 

 inner angles of the orbits equalling more than half the width of the 



* MtrcoTTov, frons ; Kipmvoi, cancer. 



