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



" Mandibles with the palp weak and slender ; the length of the second joint sur- 

 passing that of the third. 1 



" First Maxilla? with the inner plate of moderate length, furnished with from seven 

 to eight plumose setae. 



" Second Maxillae elongate, narrow. 



" Maxillipeds having the outer plate armed on the inner margin with many strong 

 teeth, which as they approach the apex are elongate, curved, and finally become setiform ; 

 the inner plate elongate, strong ; the palp short and narrow ; the outer plate extending 

 beyond the second joint of the palp. 



" The body compressed ; the back carinate ; the keel on several segments forming 

 backward-directed teeth ; the head with a long curved rostrum, compressed or sub- 

 depressed ; the side-plates not very deep, sometimes rigid, plumose on the lower margin, 

 the last two segments of the pleon coalesced. 



"Lower Antennas longer than the upper. 



" First and Second Gnathopods with the hand small. 



" Second Uropods shorter than the third. 



" Third Uropods with the peduncle shorter than the telson ; the rami equal. 



" Telson cleft." 



Atylus homochir, Haswell (PL LXXIV.). 



1885. Atylus homochir, Haswell, Proc. Linn. Soc. N.S.W., vol. x. pt. i. p. 7 (sep. copy), pi. xiii. 

 figs. 5-7. 



A sharp slender rostrum projecting a little beyond the triangular lateral lobes of the 

 head, below which its lower angles are acutely produced ; the whole of the back sharply 

 carinate, the carina continuous from the tip of the rostrum to the end of the third pleon- 

 segment, except that the seventh perseon-segment and the first three segments of the 

 pleon are distally produced in minute teeth ; the carina of the fourth pleon-segment forms 

 two teeth, the hinder one the larger ; the hinder part of the dorsally coalesced fifth and 

 sixth segments is also produced into a large tooth, with a spine-tooth on the centre of 

 its dorsal line, and separated by a small depression from that narrow front part of the 

 segment which carries the second uropods ; the postero-lateral angles of the first three 

 segments of the pleon produced into small points, above each of which is placed a spine, 

 but the lower convex lobe of the hind margin in each segment swells out beyond the 

 lower angle ; many submarginal spines on the lower margins of these segments. The 

 integument with a scale-covered appearance. 



Eyes oval or reniform, retaining colour in spirits, situate near the convex margin of 

 the head between the rostrum and the lateral lobes, ocelli numerous, rather elongate. 



Upper Antenna}. — Peduncles carinate, first joint long, about twice the length of the 



1 Not so in all species, e.g., Atylus homochir and Atylus sicummerdamii. 



