1877.] CRUSTACEA, CHIEFLY FROM SOUTH AMERICA. 667 



flexed backward on the sides, with the posterior mardns augulate- 

 excavate. Ternimal segment of the tail about as broad as lonl. with 

 the sides excavated ; upper surface flat, with a shallow depression on 

 each side, and a small median pit near the base. Antennse with the 

 flagellum much shorter than the last joint of the peduncle, with the 

 first joint the shortest. Basal joint of the uropoda (viewed from 

 above) oblong, terminal (apparent lateral) joint quite minute. 

 Colour light grey. Length 10^ lines. 



Hab. Nicaragua, S. Juan (Sa/le). (Coll. Brit. Mus ) 



Ihis species IS remarkable for its large size ; it is larger than any 

 other species of the genus in the British- Museum collection. In the 

 prominent anterior margin of the head, beneath which the antennae 

 are partly conceded. It resembles the genus Pi/rffoniscm, Kinahan, 

 which, I may add is wrongly referred by Dr. Kinahan to the Por- 

 llikdtoljuTaris ' *=''"^^^"^y to ^^^ Armadillidce, and is nearly 



Family Oniscid^. 



Subfamily Oniscin.«. 



PoRCELLio, Latreille. 

 ^«m ?^'^1«"'-^ (Mem. Soc. Phys. et Hist. Nat. Gen&ve, xiv. pp. 477. 

 4S0), has based the characters of his primary sections of this genus 

 on the form of the segments of the body. These appear to me at 

 Sio'ns "^* characteristic, that I adopt them as subgeneric 



Subgenus Porcellio. 



Postero-lateral angles of all the segments of the body acute, and 

 produced backward. •' ' 



Porcellio cayennensis, sp. n. (Plate LXVIII. fig. 2.) 

 Moderately convex, with the segments somewhat laterally pro- 

 duced, and separated from one another toward the lateral margins 

 everywhere closely and finely granulated, with larger granules, not 

 extending far toward the lateral margins on each segment. Head 

 small transverse-oblong, deeply encasedin the first segment, stronelv 

 granulated, with the antero-Iateral lobes very prominent, concfv"e 

 above, and subacute at the extremity. Eyes small. All the segments 

 of the body with the antero-Iateral angles rounded; the posterior 

 margins excavated on the sides towards the postero-lateral angle 

 which IS acute and produced backward; seventh segment with the 

 posterior margin regularly excavate. Segments of the tail short 

 with the lateral portion angularly flexed backward, the laterally 

 flexed portion in the third segment equalhng one third the width of the 

 segment ; terminal segment somewhat T-shaped, longer than broad 

 subacute at the extremity, and produced beyond the extremity of 

 the basal joint of the uropoda. Antenna wanting. Colour li^ht- 

 yellow and brown variegated. Length i inch, breadth i inch. ° 



Hab. Cayenne. 



In neither of the two specimens in the collection is the terminal 



