660 THE VOYAGE OF H.M.S. CHALLENGEE. 



foliaeeous at the base, and separated into two divisions ; the inner, which consists of a 

 small, narrow branch of great tenuity, projects a little beyond the preceding lobes, 

 Avhde the outer is broader, of extreme tenuity, and has the outer margin fringed 

 with delicate ciliate hairs, and the inner traversed by a thicker margin that is 

 prolonged into a fine subcylindrical process, sparsely fringed with hairs, which become 

 more important towards the outer distal extremity ; the third or outer branch is 

 membranous and separated into au anterior and a posterior division ; the anterior 

 is flexible, long, narrow, and tapers to a small tooth-like point, while the posterior 

 is broad, flat, ovate, and flexible. 



The first pair of gnathopoda is subpediform ; the coxa supports a rudimentary 

 mastigobranchia, which terminates in two small rami ; attached to the base there is a 

 short and thick but well-developed podobranchial plume, and attached to the mem- 

 branous articulation a small arthrobranchial plume ; the basis carries a slender branch 

 twice the length of the appendage ; next to the basis follow two broad stout joints, 

 which I take to represent the ischium and meros, the carpos, so far as I am able to decide, 

 being fused with the propodos. The propodos is long, ovate, squamous, and concave, 

 and has the outer lateral margin reflexed against that of the preceding joints, the inner 

 or median margin approximating to the corresponding margin on the opposite appendage, 

 and is thickly fringed with hairs and long, smooth spines ; the dactylos is represented 

 by a narrow joint that articulates in its entire width with the propodos, at its distal 

 extremity it is short, broad, and thicker than the propodos, the inner surface being 

 fringed with a thick brush of long, stiff hairs. 



The second pair of gnathopoda is long, slender and pediform ; the coxa carries no 

 branchial plume and only the rudiment of a mastigobranchia, above the base of which 

 is a large, projecting, disc-like plate, the significance of which I have not been able to 

 determine ; the basis is short and carries an ecphysis less than half the length of the 

 next succeeding joint, which probably represents the ischium and meros combined. The 

 next joint is more slender than the preceding and about half its length, and I presume 

 represents the carpos ; that which represents the propodos is shorter than the preceding, 

 and gradually tapers to a point, which is armed with one or two small spines ; the 

 margins are fringed with hairs. 



The first pair of pereiopoda resembles the second jrnir of gnathopoda in form, but is 

 more slender owing to the meros and carpos being much longer ; the dactylos is reduced 

 to a mere point. The second pair of pereiopoda has the carpos on the left side nearly 

 twice as long as that on the right. The third pair of pereiopoda is long ; the meros 

 reaching to a level with the distal extremity of the scaphocerite ; the carpos is nearly as 

 long as the meros ; the propodos is a little more than half the length of the carpos ; the 

 dactylos is short and sharp-pointed, terminating in a distinct unguis. The fourth and 

 fifth pairs resemble the third in form, but each is successively shorter. 



