22G AMPniroDA normalia. 



In several specimens that I have examined, the teeth upon the 

 doi-sal surface vary from strong processes to others which are rudi- 

 mentary or obsolete. 1 therefore think we are justified in concluding 

 that G. jyin-pin-atns differs from G. dent a fvs only in the former having 

 the teeth upon the first segment rudimentary. The smaller size of 

 the second pair of gnathopoda in G. purpuratus appears to be merely 

 a sexual distinction. 



2. Megamcera serrata, n. s. (Plate XXXIX. fig, 5.) B.M. 



Pleon ha\-ing the posterior dorsal margin of each segment posteriorly 

 produced and serrated ; the third segment ha\T.ng the infero-lateral 

 posterior mai'gin also serrated. Eyes small, round, black. Superior 

 antennas half the length of the animal ; first joint of the peduncle 

 longer than the cephalon, second longer than the first, third 

 shorter than either. Inferior antennae having the peduncle nearly 

 as long as the pedimcle of the superior. First pair of gnathopoda 

 small ; cai-pus as long as the propodos ; propodos long-ovate, palm 

 oblique, not defined. Second pair of gnathopoda much larger than 

 the fii'st, having the meros produced inferiorly to an acute angle ; 

 carpus short, continuous with the propodos ; propodos long-ovate, 

 palm oblique, defined by a smaU tooth; dactylos arcuate. Pe- 

 reiopoda subequal. Posterior pair of pleopoda (wanting). Telson 

 double. 



Length ^ths of an inch. 



Hab. Flinders's and Hummock Islands, Bass's Straits, in sea- weed 

 on a sandy beach (Mr. F. M. Rayner). 



3. MegamcBra semiserrata, n. s. (Plate XXXIX. fig. 6.) B.M. 



Body long and slender, having the infero-posterior margin of the third 

 segment of the pleon serrated. Eyes narrow, reniform. Superior 

 antennas half as long as the animal ; first and second joints of the 

 peduncle longer than the third. Inferior antennae not longer than 

 the peduncle of the superior. Gnathopoda resembling each other 

 in form ; first pair about half the size of the second : second pair 

 moderately large, having the cai-pus nearly as long as the propodos ; 

 propodos not broader than the carpus, long-ovate ; palm oblique, 

 slightly denticulated, and imperfectly defined ; carpus and pro- 

 podos fringed with fasciculi of hairs ; dactylos short and ciu'ved. 

 Coxae of the gnathopoda, as well as those of the first two pairs of 

 pereiopoda, furnished with a single tooth near the posterior ex- 

 tremity of the inferior margin. Last three pairs of pereiopoda 

 slightly increasing in length posteriorly, and having the posterior 



