PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 349 



The three first segments of the peduncle of the antenna are very 

 short, the three together being scarcely longer than the fifth segment. 

 The first segment is loosely articulated with the sternum of the anten- 

 nal segment, so as to be freely movable upon it; it is very short upon 

 the outside, but expands somewhat on the inner side, which terminates 

 distally in a thin tubular process {a, figure 2) arising from the oral side 

 of the segment and directed upward to a level with the dorsal side so 

 that, in the ordinary position of the appendages, its orifice is closed by 

 contact with the first segment of the peduncle of the antennula. This 

 tubular process readily admits a large bristle which can be juished 

 through it round into the cavity of the segment itself. It undoubtedly 

 contains the canal of the green gland. The second segment is small, 

 closely united with the third, and bears upon its outer side a slender 

 scale-like appendage («, figure 1) which reaches nearly to the tip of the 

 peduncle, is about five times as long as broad, and thickly ciliated along 

 both edges. The third segment, as seen from below, is almost wholly 

 internal to the second, and is armed on the distal part of the inner mar- 

 gin with a small spiniform tubercle. The fourth and fifth segments are 

 subcylindrical, the fourth is slightly longer than the fifth, and both are 

 ciliated each side. The flagellum is about as thick at base as the major 

 flagellum of the antennula, but tapers rather more rapidly and is prob- 

 ably considerably shorter. 



The buccal opening is nearly square. The branchiostergites extend 

 forward quite over the sternum of the antennary somite, and their an- 

 terior extremities are apphed to the basal segments of the antennse, 

 which, however, are freely movable upon the antennary somite. The 

 epistorae is short, not extending at all in front of the bases of the an- 

 tennae, is nearly on a level with the dorsal wall of the efferent passages 

 from the branchial chambers and on a plane above the bases of the an- 

 tennae, so that the efferent passages terminate in the space between the 

 upturned edges of the squamiforra processes of the inner sides of the 

 basal segments of the antennulse and just beneath the short two-spined 

 rostrum. In the middle of the slightly raised and regularly arcuate 

 posterior edge of the epistome there is a slight elevation with a tuft of 

 hairs, as described and figured by Willemoes-Suhm in Willenioesia lepto- 

 dactyla. The anterior part of the endostome is on a plane somewhat 

 above the ])laneof the epistome, but the space below is filled by the soft 

 and fleshy labrum which ]>rojects considerably below the raised i)osterior 

 edge of the epistome, and does not differ essentially from the labrum in 

 Astacidae or Scyllaridce. 



The mandibles are apparently wholly without molar areas, and ex- 

 pand into very broad and thin lamella) sharply serrated along the cut- 

 ting edges. The mandibular palpus is short and apparently composed 

 of only two segments, the distal being shorter than the proximal. There 

 may be an additional short basal segment, which I am unable to dis- 

 cover without injuring the specimen, so that the palpus may prove to 

 be triarticulate. 



