646 



THE VOYAGE OF H.M.S. CHALLENGEK. 



abdominalis, Kroyer, but differs in having the branchial plates of the female pointed 

 at the extremity, instead of being rounded as in the typical specimens. 

 Both specimens were gravid with an enormous number of ova. 



Plesionika spinipes (PI. CXIII. fig. 2). 



Carapace smooth ; rostrum about twice the length of the carapace, serrate on the 

 upper and lower margins. 



Pleon smooth. 



Telson slender ; armed with two or four spines at the terminal extremity and three 

 small ones on the dorsodateral surface. 



Pereiopoda slender and longer than the body of the animal, the three posterior pairs 

 extending beyond the extremity, and having the meros posteriorly armed with spines. 



The scaphocerite about half the length of the rostrum. 



Habitat. 



north of New Guinea ; depth, 150 fathoms ; bottom, coral mud. Eight specimens ; seven 

 males, one female. Trawled. 



This species has the rostrum very straight, and finely and evenly serrate on the upper 

 and lower margins with small closely packed teeth that have their apices directed forwards. 

 The serrature on the upper surface commences on the anterior portion of the gastric 

 region, that on the under margin begins a little in advance of the eye. The rest of the 

 surface of the carapace is smooth. Two small teeth, one corresponding with the first pair 

 of antennas, the other with the fronto-lateral angles, stand on the frontal margin. The 

 pleon is smooth and free from markings of any kind ; the third somite is slightly arcuate. 

 The telson is narrow and laterally compressed, the dorso-lateral angle being furnished 

 with three small spinules, seen best in a lateral aspect, and there are two or three longer 

 ones at the extremity. 



The ophthalmopoda are of moderate size and stand on short pedicles. 



The first pair of antennas has the first joint deeply excavated to receive the ophthal- 

 mopod, and is furnished on the outer side with a sharp stylocerite ; the second and third 

 joints are short, and terminate in two unequally long nagella. the shorter of which passes 



