CRTTSTACEA OF THE MEEGITI ARCHIPELAGO. 291 



as, e.'y., tlae dorsal mediaa ridge, a lateral longitudinal ridge 

 proceeding from the hepatic spine to the posterior margin, the 

 posterior margin itself, &c., so that the pubescence appears 

 only on those parts of the outer surface which are slightly im- 

 pressed. 



The rostrum is very short, and reaches only halfway to the 

 end of the eye-peduncles ; it is strongly laterally compressed, 

 tolerably high, and the lateral surfaces are pubescent. The 

 upper margin of the rostrum is slightly declivous towards the tip, 

 which is acute ; it is armed above with six small acute teeth, 

 which gradually decrease in size towards the tip. These six teeth 

 are about equidistant ; the anterior tooth is placed close to the tip, 

 and the three posterior ones are situated on the dorsal surface of 

 the carapace, the fourth being placed precisely above the frontal 

 margin ; the upper margins of these six teeth are microscopically 

 crenulate and fringed with short hairs. They are preceded 

 by a seventh small acute tooth found at the base of the 

 rostrum, a little before the middle of the cephalothorax. The 

 slightly ascending lower margin of the rostrum is entire and 

 unarmed. The rostrum is continued backwards into a smooth, 

 glabrous, blunt, scarcely elevated ridge, which divides imme- 

 diately before the posterior margin of the carapace into two ridges, 

 which proceed towards the posterior margin. In P. Rielitersii 

 the two posterior teeth of the rostrum are situated on the dorsal 

 surface of the carapace. 



The anterior margin of the cephalothorax is armed with an 

 acute antennal spine and with a small supraocular tooth ; there 

 is also a small hepatic spine. The antennal and hepatic grooves 

 are scarcely indicated ; but the gastro-hepatic sulcus, which pro- 

 ceeds from the hepatic spine obliquely upwards and backwards 

 towards the middle of the dorsal median ridge of the carapace, 

 is distinctly marked. The antero-inferior angle of the cephalo- 

 thorax is not toothed. The eye-peduncles are very short, and 

 scarcely reach to the distal end of the antepenultimate joint of 

 the antennulary peduncles ; the latter are a little shorter than 

 the antennal scales. In nearly all these specimens the flagella of 

 the internal antennsB are unfortunately broken off; in a single 

 specimen only are they still partly preserved. These flagella 

 are, as I suppose, about as long as their peduncles ; the outer or 

 upper one is much thicker than the other, but it soon tapers 

 a little beyond the tips of the antennal scales. The peduncles of 



19* 



