REPORT ON THE CRUSTACEA MA CRURA. 877 



The first pair of antennae has the peduncle reaching to about half the length of the 

 rostrum, and terminates in two short, immature flagella. 



The second pair of antennae has the peduncle reaching nearly as far as the distal 

 extremity of the eye, and has the second joint armed with a long, spine-like tooth on 

 the outer distant angle, and on the inner with a long and slender foliaceous scaphocerite, 

 fringed on the inner margins with long hairs. The flagellum is in an immature 

 condition, and does not reach to the extremity of the scaphocerite. 



The mandibles have no synaphipod. 



The second pair of gnathopoda is six-jointed, and carries a basecphysis that reaches 

 to nearly the extremity of the. meros ; the succeeding joints are subequal, the terminal 

 one being more slender than the preceding, somewhat shorter, and tipped with hairs. 



The first pair of pereiopoda is slender at the base, and carries a two-jointed 

 basecphysis, tipped with long hairs. It gradually increases in diameter until it reaches 

 the broadest part at the distal extremity of the carpos, whence to the distal extremity of 

 the palm of the propodos the width gradually lessens, and the inferior angle projects to 

 a small point which represents the pollex, against which the longer dactylos impinges. 

 The second pair of pereiopoda, although tolerably robust, is much more slender than 

 the first pair, and terminates in a simple dactylos ; like the preceding it is furnished 

 with a biarticulate basecphysis. The following three pairs of pereiopoda are more 

 slender than the second, and terminate in a sharply pointed, simple dactylos ; 

 each pair is furnished with a biarticulate basecphysis, that is slightly longer than the 

 preceding. 



The pleopoda are still in an immature condition, and are all biramose, except the 

 first pair, which appears to be wanting. The posterior pair, which forms part of the 

 rhipidura, has the two branches subequal but neither as long as the telson. 



Observation. — It is almost impossible as yet to determine what may be the adult 

 characters of the specimens of which this and the following species are the undeveloped 

 forms. 



Oodeopus serratus, n. sp. (PI. CXLII. figs. 2, 3). 



Carapace smooth, dorsally depressed in the gastric region, anteriorly produced to 

 a horizontally directed rostrum that is slightly waved and serrate on the lateral 

 margins. The orbit is excavate to the infero-lateral angle, which is produced to a 

 small but acute point, whence the lateral margin is serrate to the posterior margin of the 

 carapace. 



The pleon is three times the length of the carapace ; the first somite is dorsally 

 smooth, the second is armed with a large laterally compressed tooth, the carina of which 

 commences at the anterior margin and terminates at the posterior, and reaches as far as 



