REPORT ON THE ISOPODA. 115 



three are produced into a short spine. Abdominal segments comparatively elongated, 

 first pair subequal ; last segment very long and cylindrical, terminating in a rounded 

 median projection. First pair of antennae with unequally sized flagella, the outer much 

 longer than the inner ; second pair of antennas with a rudimentary exopodite, setose ; 

 chelae extremely slender, with a minute three-jointed exopodite ; fossorial limb stout 

 and strong, also with a rudimentary exopodite. Abdominal limbs well developed, 

 with a two-jointed exopodite ; uropoda long, with a mrdtiarticulated endopodite and 

 exopodite, the former considerably longer than the latter. 



This genus is closely allied to the last, and is as it were an exaggerated likeness of 

 it ; the slenderness of the body is more marked in the present genus, the rostrum 

 and the various spines which exist along the sides of the body in the last genus are here 

 much more strongly marked. 



The remarkable form of the chelae and the presence of an exopodite on these and the 

 following pairs of appendages serve, however, to distinguish Leiopus from Typhlapseudes ; 

 the latter character connects Leiopus more closely with Apseudes, but the extreme 

 slenderness of the chelae is peculiar to the genus. 



As in Typhlapseudes there appears to be no great distinction in Leiopus between 

 the males and females. 



Leiopus leptodactylus, F. E. Beddard (PI. XV. figs. 5-12 ; PL XII. fig. 1). 

 Leiopus leptodactylus, F. E. Beddard, Proc. Zool. Soc. Lond., 1886, pt. i. p. 116. 



This species is represented by a large number of individuals, dredged in the North 

 Atlantic from a depth of 1000 fathoms. 



The largest specimens attain a length of 1 3 mm. 



The body is flattened, depressed, extremely elongated and narrow, it is wider 

 anteriorly and gradually diminishes posteriorly. 



The cephalothorax, comprising the head and the first segment of the thorax, is rather 

 more than twice the length and about equal in breadth to the first free segment of the 

 thorax. The head is prolonged in front into a long rostrum ; laterally are the two ocular 

 lobes which are large and conspicuous and pointed anteriorly ; there is no trace of any 

 eyes. Behind the ocular lobes are two longish spiny processes which represent the 

 epimera of the first thoracic segment ; they, as well as the ocular lobes and the rostrum 

 are much more developed than in the last species. The dorsal surface of the head is 

 convex anteriorly as well as posteriorly by reason of the paired postero-lateral convexities. 



The first segment of the thorax is as wide as the head, the following segments 

 decrease in width, the first of them suddenly, the rest more gradually ; the length of 

 these segments increases up to the fourth, the fifth being subequal in length to the 

 fourth, and the sixth rather shorter. 



