ISOPODA OF THE 'LIGHTNING' AND OTHEE EXPEDITIONS. 89 



The pleon has the epimera produced into small spines, which are more conspicuous 

 on the two anterior segments. Sixth segment as long as three preceding, its termination 

 truncate and emarginate. 



The upper antenna? have the large basal joint three-sided, and partially serrulate on 

 the upper edge. 



The first legs have the basos short and distally thickened, with a small tooth on the 

 hinder margin ; hand (u. gn 1 ) not unlike that of A. simplicirostris, the basal portion 

 broadly triangular, the thumb inclining outwards, with a tooth rising in the hollow to 

 meet the overreaching finger, the nails of both thumb and finger long. 



The second legs (n. gn 2 ) are long, the basos produced, meros with one infero-posteal 

 and two infero-anteal spines ; carpus with three spines on the hinder and four on the 

 front margin ; hand with four spines confined to the distal half of the hinder margin, 

 and seven front spines, the first of which is minute, the rest subequal ; finger with 

 three minute teeth on its edge. All the spines of the limb are of slender character, 

 and there is a total absence of the cilia, which in most allied species take part with the 

 spines in the garnishing of the lower joints of this limb. 



All the remaining limbs are remarkable as differing from those usual in the genus 

 by their more delicate and simple structure, there being a marked absence of that 

 elaborate and diverse ornamentation of spines, seta?, and cilia so characteristic in the 

 genus. This will be evidenced in the following description of the last pair of legs. 



The last legs (n. prp 5 ) are slender and delicate in structure ; the basos narrow and 

 long, and perfectly glabrous (without spines, setae, or cilia), is as long as the three 

 following joints combined ; ischium very short ; meros shorter than carpus, the 

 former with one, the latter with two cilia at distal extremity of front; hand long, 

 narrow, about six times as long as broad, and subequal in dimensions to the wrist, 

 with a single slender spine midway on the front margin, and two long, slender, simple 

 spines at the origin of the very long and very slender finger, which has a small cilium 

 at one third its length on the outer, and a more distant toothlet on the inner margin. 



The pleopods, with one exception, were abraded in our specimen, the one that 

 remained was a very delicate slender organ. 



Length 6 millim. 



A single example was dredged in the ' Porcupine ' Expedition of 1870, just west of 

 the African side of the Straits of Gibraltar, in 128 fathoms (Station 37, lat. 35° 50' N., 

 long. 5° 26' W. ; bottom temperature 54° Fahr.). 



6. Apsetjdes lunakifrons, n. sp. (Plate XVII. fig. n.) 

 ? Apseudes echinatus, G. O. Sars, " Isopoda chelifera," Archiv for Math, og Natuxvid. vii. 1882, 

 p. 13. 



A remarkable species on account of the great irregularity of the dorsal surface of 

 carapace and perteon, and of the lateral margins of the segments of the latter. 



