126 CRUSTACEA. 



ACANTHONYX SIMPLEX. 



Feminaa : A. Petiverii affinis. Carapax parce convexus, tuberculis 

 omnino carens, marginibus lateralibus parallelis, postering cum denti- 

 bus duobus obsoletis ornatis, dente post-orbitali nullo. Pedes antici 

 reliquis parce crassiores, digitis plerumqiie conliguis, 7-8-denticulatis, 

 denticulis triangulatis, carpo supra cristato, subacuto; paris postici 

 articulus penultlmus angustior, angulo inferiore basi nee apici propin- 

 quiore. Tarsus 8-10 spimdis armatus. 



Female: Near Petiverii. Carapax sparingly convex, without a trace 

 of tubercles; lateral margins parallel; no post-orbital tooth, but 

 having posteriorly two obsolete teeth. Anterior feet sparingly 

 stouter than the following ; fingers contiguous, except near base ; 

 seven or eight triangular teeth; carpus cristate and subacute above. 

 Angle on inferior side of penult joint of posterior legs nearer base 

 than apex. Tarsus armed with eight to ten spinules. 



Plate 5, fig. 4 or, female, enlarged two diameters ; b, first pair ; c, 

 extremity of second pair ; d, extremity of posterior pair. 



Sandwich Islands. 



Length of carapax, seven lines; width, five lines; breadth across the 

 eyes, two lines. A very minute and sparse pubescence is seen, with a 

 lens, on the legs, after the specimen is dry. The anterior angles of the 

 carapax and the teeth posteriorly on the margin, seem, at first sight, 

 to be prominent and acute ; but this, as in other species, is owing to 

 the setae with which they are furnished. The distance between the 

 two teeth referred to, is a little more than half the distance from the 

 anterior of the two to the angle of the carapax. The spinules of the 

 tarsus are less numerous and not as close as in the Petiverii, which 

 species it resembles in its cristate carpus. The outer antennas lie 

 alongside of the beak, and do not project beyond the setae at the apex 

 of the beak. The abdomen of the female is broad elliptical, but larger 

 and more nearly circular when with eggs beneath. In one specimen, 

 possibly a different species, the carpus is not cristate. 



