ISOPODA OF THE 'LIGHTNING' A^'D OTHER EXPEDITIONS. 85 



3. Apseudes spinosus (M. Sars). (Plate XVII. fig. i.) 



Rhcea spinosa, M. Sars, Overs, over Norsk-Arktiske Region forekom. Krebsdyr (Vidensk. Selsk. 



Forhandl. 1858), p. 30. 

 Apseudes talpa, Lilljeborg, Bidr. till Kami. Sverige och Norrige forekom. Isopodernas och Tanai- 



dernas Familij, 1864, p. 9; G. O. Sars, Nye Dybvandscrustac. fra Lofoteu (Vidensk. Selsk. 



Forhandl. 1869), p. 45 (nee A. talpa, Montagu, nee A. talpa, Bate & Westwood). 



Female (i. d). Frontal region much produced into a long acute rostrum, nearly half 

 as long as the long basal joint of the upper antennae ; this rostrum is expanded greatly 

 towards the base into rounded lateral bulb-like lobes, and deeply excavated centrally 

 above (i. l), the sides being as it were upturned. 



Ocular processes or alae rather shorter than usual, broadly triangular, no vestige 

 of eyes. 



Carapace widening rapidly behind the rostrum, forming nearly a square ; lateral 

 margins slightly sinuous, and produced to a point in front, at the ocular suture. 



First two free peraeon-segments as broad as the carapace ; third narrower but longer, 

 the two following of still less width, but greater length, the last somewhat narrower 

 and much shorter than the two which precede it ; the antero-lateral margins of all 

 these segments are produced outwards into conspicuous triangular pointed processes 

 beset with verticillately plumose setae ; each segment of peraeon and pleon has a central 

 spine on the underside, and there is also a long acute spine upon the epistoma (i. l). 



Pleon having the first five segments short, their epimera (i. pi.) produced directly 

 outwards into greatly developed and conspicuous spike-like processes, each furnished 

 with eight or ten very long verticillately plumose setae ; these setae protrude directly 

 over similar setae of the pleopoda, and thus with them form a dense and elegant mass 

 of plumage on each side of the pleon. The sixth segment is very long, equalling the 

 united length of the five segments preceding, a little irregular in outline, without being 

 decidedly spined ; from small protuberances issue verticillately plumose setae, the segment 

 narrows before reaching the points of attachment of the uropods, and then starting from 

 a small ciliated tooth it widens rapidly for the attachment of the uropods, and subse- 

 quently ends obtusely. 



The upper antennae (i. d) have the basal joint long and narrow, about five times as 

 long as broad, with two longitudinal grooves on the upper surface which leave, as it 

 were, a central and lateral rib, basal portion of inner margin finely serrated, in advance 

 of this and at a point where the joint narrows a group of cilia spring; second joint 

 about one third as long as the first, stout, distally dilated ; third somewhat shorter 

 and much thinner than second ; fiagellum longer than the peduncle, its articulations 

 20-22 ; secondary appendage more than half the length of the fiagellum, consisting of 

 10 long articulations. 



The lower antennae (i. a.i) having the first short joint internally lobed, inner margin 

 of the lobe bearing minute spines ; second joint two fifths the length of the first joint 



VOL. sii. — PAET IV. No. 2. — October, 1886. P 



