290 CRUSTACEA. 



ARENJEUS CRIBRAEIUS, (Lamk.) Dana. 



Plate 18, fig. 2 a, under view of mouth, the outer pairs of organs 

 removed showing, e, the anterior margin of the buccal area mx, the 

 summit of the inner branch of the first maxillipeds md, the man- 

 dibles without the mandibular palpi; b, one of the outer maxillipeds. 



Rio Janeiro, Brazil. 



Length of carapax, one inch seven and a half lines ; breadth be- 

 tween tips of long lateral spines, three inches and six lines ; ratio of 

 length to this breadth, 1 :2'15; breadth between the teeth next an- 

 terior, two inches ten and one-fourth lines ; ratio of length to this 

 breadth, 1 : T76. 



The habits of this species are different somewhat from the true 

 Lupas, the individuals being found along the sandy beaches, about 

 the harbour of Rio, a peculiarity to which the name of the genus 

 alludes. The colour of the carapax, to which the specific name refers, 

 has a reticulated arrangement, there being a fine network of a pur- 

 plish slate-colour on a pale yellowish ground; on the arm and hand 

 the areolation is larger. The two teeth of the front either side of the 

 middle are smaller and are united so as to form a doubly-pointed 

 tooth, the inner point a little the longer. The arm is rather short, 

 and has three spines on its anterior margin. 



Portunus cribrarius, LAMARCK, v. 259. 

 Lupa cribraria, EDWARDS, i. 452. 



FAMILY V. PLATYONYCHID^E. 



Palatum lined elevatd utrinque non subdivisum. Ramus maxillipedis 

 Imi internus simplex. Carapax angustus. Abdomen maris basi 

 angustum. 



