THE NEW-YORK FAUNA. 



CLASS VII. CRUSTACEA. 



OVIPAROUS ARTICULATED ANIMALS, WITH THE BODY DIVIDED INTO MOVABLE RINGS MORE OR 

 LESS DISTINCT J OUTER COVERING CALCAREOUS OR MEMBRANOUS, MORE OR LESS SOLID. 

 MOST COMMONLY A HEART AND BLOODVESSELS, WITHOUT ANY INTERNAL SKELETON PROPER- 

 LY SO NAMED. A DOUBLE SERIES OF MEMBERS, SUCH AS ANTENNAE, JAWS, FEET, etc. AL- 

 MOST ALWAYS DISTINCTLY ARTICULATED. EYES VARIABLE IN NUMBER, EITHER SESSILE OR 

 SUPPORTED ON LONG PEDICELS. SEXES DISTINCT. FEET GENERALLY FROM FIVE TO SEVEN. 

 RESPIRATION GENERALLY AQUATIC BY THE GILLS, OR REPLACED BY THE SKIN. INHABIT 

 LAND, OR FRESH AND SALT WATER. 



ORDER I. DECAPODA. 



Branchice lamellar, of a pyramidal form, beneath the body and attached to the sides of the 

 thorax, enclosed in special respiratory cavities. Eyes two, pedunculated and movable. 

 Almost always five pair of ambulatory or prehensile thoracic feet. 



Obs. This order is usually divided into two groups, namely, the Brachyura and Macroura, 

 of which the common Crab and the Lobster stand as the respective types. Recent writers 

 have introduced a third group Anomoura, which is intermediate between the two, and forms 

 a passage from one to the other. 



GENUS LIBINIA. Leach. Edwards. 



Shield vaulted, orbicular or pyriform ; rostrum notched at its extremity. Eyes scarcely 

 thicker than their peduncles. Exterior antennas as long as the rostrum ; first joint longer 

 than the second. Anterior feet thicker than the others ; the pincers closing completely. 

 Fauna — Part 6*. 1 



