RETORT ON THE CRUSTACEA MACRURA. 867 



together tliey do not quite equal the first in length. The outer and upper flagellum is 

 swollen at the base for a short distance, and then gradually narrows to a diameter which 

 corresponds with that of the lower flagellum, and the under surface of the enlarged 

 portion is flat or hollowed, and carries a mat of membranous cilia. 



The second pair of antennae carries a scaphocerite that is long, narrow, and has the 

 two margins correspondingly curved to meet at the extremity, where the outer is 

 produced to a small tooth ; the outer margin is smooth and rigid, and the inner 

 thickened by a fringe of strong hairs ; the ultimate joint of the peduncle is half the 

 length of the scaphocerite, and much stouter than the flagellum, which is about half the 

 length of the animal. 



Behind these latter appendages in the median line the epistoma projects in the form 

 of a laterally compressed, anteriorly directed, lobedike beak, between which and the 

 metastoma the mandibles are enclosed. 



The mandibles (PI. CXLI. fig. id) are short, broad, and shell-shaped, and consist of 

 the psalistoma only, the molar process and synaphipod being absent. 



The first pair of siagnopoda (fig. le) is small and three-branched ; the outer branch 

 is subcylindrical, unarmed, except for two hairs, one short and simple and the other 

 extremely long and minutely serrate ; the middle branch is broad and armed with long, 

 strong, curved spines, and the inner branch is short, and armed with short, straight spines. 



The second pair of siagnopoda (fig. If) consists of a broad, foliaceous plate of 

 considerable tenuity, surrounded with hairs that radiate as from a common centre, all 

 bending towards the anterior apex ; on the inner end, attached to the plate as part of 

 the same structure, is a short, subcylindrical branch, tipped with three or four minutely 

 serrate hairs. 



The third pair of siagnopoda (fig. \g) consists of a long, foliaceous plate of considerable 

 tenuity ; the basal part has the outer portion separated by a broad, imperfect articula- 

 lation, from which the structure gradually narrows towards the extremity, forming a 

 long acute triangle, the distal portion of which forms the apex, and is divided from the 

 rest by an obscure articulation, at the base of which on the inner side is a toothdike 

 prominence ; the margin is distally fringed with long hairs that increase in length 

 towards the extremity. 



The first pair of gnathopoda (fig. \h) is six-jointed, subpediforra, short, narrow, and 

 cylindrical ; the coxa is short and stout, the basis is longer, and the ischium is long and 

 narrow, and slightly flattened ; the meros resembles the ischium, and the carpos is short, 

 triangular, and articulates with the meros at a right angle. The propodos is long, cylin- 

 drical, and reflexed ; the dactylos is broad, distally attached to the propodos, and directed 

 posteriorly, and is fringed with short, stout spinules on the outer margin, and apically 

 with one long and straight. This appendage is so closely associated with the preceding, 

 that to all appearance the two are connected as represented in the Plate. Even when 



