5fi6 REV. T. R. R. STEBBING ON CRUSTACEANS [MilJ 22, 



TiiiCHONiscus MAOELLANicus (Daua). 



1853. Styloniscua magellanicus, Dana, U.S. Expl. Exp. vol. xiii., 

 Crust, p. 730, pi. 48. figs. 7 a-g. 



1881. Styloniscus magellanicus, Miers, Pr. Zool. Soc. Lond. p. 77. 



1885. iSti/lomscus magellanicus, Budde-Lund, Crust. Lsop. Ter- 

 restria, p. 271. 



Body smooth, narrowly elliptical ; fi-ont angles of first perseon- 

 seguient rounded, not greatly produced, hind angles of this and 

 next segment rounded, of third subquadrate, of the rest successively 

 a little more and more produced backwards and sharpened, but in 

 none absolutely acute ; first the longest, rather longer than the head, 

 the others having the side-plates marked by a faint, obliquely 

 sinuous suture. Pleon abruptly narrower than perseon, second 

 segment very short. Telson with sides converging from insertion 

 of uropods almost straight to broadly truncate apex. 



Eyes dark, wilh three visual elements. Eirst antennae with 

 second joint shorter tfian first or third. Second antenntx? spiniilose, 

 with joints of peduncle successively longer, the last a little shorter 

 than the 7-10-jointed flagellura (7-8-jointed in specimens ex- 

 amined), last joint tipped with fascicle of setae. 



Upper lip apically rounded and furred. Mandibles with toothed 

 cutting-edge narrow ; a single seta on right mandible ; molar cylin- 

 dric, prominent. First maxillae : inner plate with three plumose 

 setaj, the inner the longest ; outer plate strap-shaped, surmounted 

 by eight unequal spines. Maxillipeds as partially figured by Dana, 

 and in near agreement with those of T.pnsillus as figured by Sars, 

 but the epipod longer and distally furred with closely-set, very 

 short setules or spinules. 



Hind trunk-legs longer than those in front, all very similar in 

 structure ; the fifth joint carrying the strongest and longest spines ; 

 the sixth fringed on the outer margin with transparent spinules, 

 with little spines at intervals, also on the inner and part of the apical 

 margin showing, especially in the hinder pairs, tliin membranous 

 expansions, as well as several spines; the small seventh joint is 

 beset v\'ith various setules, among them along one with split apex, 

 and others with smoothly widened extremity (compare Chilton on 

 Fhih/r/ria, 1886). In the second pleopods of the male the long 

 distal joint of the inner ramus is, till ne;ir the end, much more 

 widened than the stiliform joint figured by Sars for tliis part of 

 T. piicimcpiis. T}\e uropods are as Dana figures them, the inner 

 ramus fully two-thirds as long as the outer, though in his description 

 he says " longer branch nearly tM-ice the length of the other." 



Colour brown, mottled with yellowish white, especially a series 

 of light patches just above the side-plates of the pera'on. Length 

 about a third of an inch, or 8 mm. 



Mr. A'^allentin's s])ecimens were " found in a damp cave on the 

 top of a hill 450 feet high, 2 miles distant from Stanley." 



[''01 



