ISOPODA OF THE ' LIGHTNINQ ' AND OTHEE EXPEDITIONS. 97 



spines of the pleon, so much reduced in size as to become almost obsolete, while the 

 ventral spines of the earlier segments of the body are as large as in the female, and the 

 hand of the first legs is not more largely dexeloped than in the other sex. All these 

 points are contrary to what is usual, and not what might have been expected to 

 characterize the male. 



The figure ([. gn^*) represents a monstrous outgrowth of the thumb in one of the 

 specimens, showing a tendency to three terminations of the thumb instead of one. 



Length half an inch. 



Specimens or fragments of Apseudes gracilis were procured in three of the dredgings 

 of the ' Valorous ' Expedition in 1875 ; the localities were : — 



Station 9, lat. 59° 10' N., long. 50° 26' W., 1750 fath., Davis Strait. 

 Station 12, lat. 56° 11' N., long. 37° 41' W., 1450 fath., North Atlantic. 

 Station 16, lat. 55° 10' N., long. 25° 58' W., 1785 fath.. North Atlantic. 



It would thus appear to be confined to the greatest depths in the abyss of the 

 Northern seas. 



Genus 2. Sphteapus \ n. g. 



Animal less elongated than in the other genera, widest at the hinder part of the 

 carapace, thence gradually narrowed behind. First two segments of peraeon coalesced 

 with the cephalon into a carapace, furnished with a simple rostrum. Epimera of 

 gnathopodal segments not produced forwards. Last segment of pleon often produced 

 to an acute point. 



No eyes. The alse minute, triangular. 



Upper antcnnEE with the basal joint of great size, long and broad, inner flagellum 

 sometimes rudimentary. Lower antennse without the scales generally characteristic 

 of this family ; slender. 



First gnathopods bulky, with the hand (in the male) set on the wrist, like a hammer 

 at right angles to its handle, and hence the generic name. 



Typical species— Sphyrapns malleolus, n. sp. 



The chief characters in this genus are the absence of the scale in the lower antennae 

 and the conjunction of the second perceon-segment with the carapace. 



Diagnosis of the Species of Sphyrapus. 



Last segment of pleon not produced. 



Epimera of pleon obtusely rounded anomalus. 



Epimera of pleon angularly pointed serratus, G. O. Sars^ 



Last segment of pleon produced to an elongated point behind. 



Second segment of pleon with greatly developed, outspread lateral 



processes malleolus. 



Second segment of pleon with lateral spines not exceeding in size those 



which are present also on the other segments ....... tudes. 



' a(l)vpa a hammer, irovs a foot. " " Habitat in magno abysso arese frigidse maris Norvegise et glacialis." 



