1542 THE VOYAGE OF H.M.S. CHALLENGER. 



front margin finely pectinate ; the fifth joint rather longer than the third, its front margin 

 pectinate. 



Fifth Perieopods. — The side-plates a little deeper behind than in front, with a 

 o-enerally semicircular appearance. The first joint widely expanded, rather longer than 

 broad, the front margin sinuous, bowed out in the middle, the hind margin very convex 

 and regular, the remaining joints small, together scarcely as long as the first, the second 

 not longer than broad, the third and fourth nearly equal, two or three times as long as 

 broad, the fifth longer than either ; the finger not half the length of the fifth joint, broad 

 at the base, the upturned tip very acute. 



Pleopods. — The peduncles broad and thick ; the cleft spine on the first joint of the 

 inner ramus having the serrate arm shorter than that with the subapical dilatation ; the 

 first joint of the outer ramus bearing a prominent, apically narrow, interlocking process ; 

 the joints of the rami from nine to ten in number. 



Uropods. — Peduncles of the first pair rather longer than the inner ramus, pectinate 

 round the outer apex ; the inner ramus larger than the outer, its outer margin pectinate 

 nearly to the apex, and the inner for a short space at a little distance from the apex ; 

 the outer ramus pectinate on both margins, more strongly on the inner ; peduncles 

 of the second pair not reaching so far as those of the first, not as long as the inner 

 ramus ; inner ramus longer and much broader than the outer, the outer margin 

 pectinate and the inner near the apex, the outer ramus with only the inner margin 

 pectinate ; these rami respectively not reaching so far as those of the first pair ; peduncles 

 of the third pair a little longer than broad, widening distally so that their inner apices 

 touch or overlap, shorter than the nearly equal rami ; the inner ramus broader than the 

 outer, rather strongly pectinate for a short space on the inner margin near the apex, and 

 less strongly on the outer margin for a longer space, the pectination on the margins 

 generally becoming very minute at the upper part ; the outer ramus pectinate along 

 almost all the inner margin but on that only ; the peduncles and rami respectively of this 

 pair reach beyond those of the other pairs. 



Telson subequal in length to the peduncles of the third uropods, longer than broad, 

 narrowing from near the base to an acute apex, with the sides very slightly convex, the 

 tip just showing beyond the peduncles of the third uropods. 



Length. — The specimen, in the bent position figured, measured one-fifth of an 

 inch ; the figures a.i.A., l.s.A., m.A., mxp.A., gn l A., were taken from parts of 

 this specimen ; the remaining figures from another specimen as nearly as possible 

 similar. 



Locality.— April 29, 1S7G, North Atlantic; lat. 18° 8' N., long. 30° 5' W. ; surface, 

 night; surface temperature, 73°7. Eight specimens, apparently all males. 



Remarks. — The specific name is given in honour of Boeck, the founder of th° genus 



