SPH^ROMID^. 399 



are inserted close together, in the middle of the front of 

 the head, and have a multiarticulate flagellum. The seg- 

 ments of the body do not exhibit, when viewed dorsally, 

 the epimera-like structure of the basal joints of the legs 

 observable in the Idoteidce. In some few species the first 

 or the first two pairs of legs are subcheliform (as in the 

 genus Ancinus) ; but the third pair are always simple. 

 In the majority, all the legs are slender, and simply formed 

 for walking, with a generally bifid terminal finger. The 

 basal segments of the tail are more or less rudimentary, 

 and in general soldered together more or less completely, 

 so as to form, apparently, only a single joint, which in 

 many species is furnished with large tubercles or spines. 

 The five pairs of branchial feet (pleopoda) are affixed 

 obliquely on the underside of the large joint of the tail, 

 which is deeply excavated for their reception. They are 

 very delicate and membranous in their structure, the 

 three anterior pairs being strongly ciliated on their 

 apical and external edges ; and the second pair, in the 

 males, are furnished with an elongated slender-pointed 

 style. The terminal pair of the tail-legs (uropoda) con- 

 sist of two horizontal plates, of which the outer only 

 is movable, the inner one being either occasionally 

 obsolete, or soldered to the basal support. They are 

 attached at the sides of the terminal joint near its 

 anterior margin. 



Professor Milne Edwards has proposed a separate 

 family {Splueromiens chelifers) for the reception of a re- 

 markable new genus {Ancinus), upon a specimen of un- 

 known locality contained in the British Museum, which 

 has the first two pairs of legs terminated by large and 

 strong hooks, and the body so flat as to be almost folia- 

 ceous. The inner plate of the lateral appendages of the 

 tail is wanting, whilst the outer is greatly elongated; but 



