458 Mr. C. Spence Bate on the British Diastylidse. 



anterior edge is considerably produced, and gives a truncated 

 character to the appearance of the animal. The margin is ser- 

 rated, anteriorly more prominently so. 



The upper antenna is v/anting ; the lower (fig. 5) is very 

 short, and consists of a peduncle of three joints and a filamentary 

 terminal appendage, the first segment of which is long and the 

 rest extremely small and fine. 



Mandible furnished with a prominent molar tubercle, but not 

 supplied with hair-like spiuules between it and the incisive 

 mai'gin. The first gnathopod (fig. 11) is pediform; the second 

 (fig. 12) also, but the basal articulation is broadly developed 

 anteriorly, so as to fulfil the office of an operculum ; the internal 

 margin is convex and furnished with strong hairs ; the external 

 margin is concave posteriorly, and extends at the anterior corner 

 into a long, firm, ciliated spine ; a second spine of the same cha- 

 racter is situated on the anterior margin between the former and 

 the terminal joints of the appendage, which consists of four small 

 segments supplied with a few plumose cilia. This pair of limbs 

 is furnished with a palpe, or secondary appendage, consisting of 

 a single-jointed peduncle and a terminal filamentary appendage 

 supplied with a brush of cilia. The next succeeding pair of legs 

 (fig. 13), the homologues of the large claw-feet of the Decapoda, 

 are extremely long, reaching considerably in advance of the an- 

 terior margin of the animal ; each of them consists of a long 

 basal joint, denticulated with four or five strong spines upon the 

 convex or inferior margin, followed by a short joint and three 

 terminal long ones : this as well as the three succeeding legs are 

 furnished with a palpe similar in formation to that of the pre- 

 ceding pair. 



The four next succeeding pairs of legs (figs. 14, 15, 16, 17) 

 are similarly formed, except that they gradually diminish in 

 size posteriorly, the last being considerably the smallest, and 

 moi'cover unfurnished with n palpe. In the female the two anterior 

 pairs of these last four are furnished with fouets, or scale-like 

 appendages which overlap each other and carry the ova and the 

 larvse. 



I have received four or five specimens of this species, which 

 were dredged by W. Webster, Esq., in Plymouth Sound, some- 

 what within the Breakwater ; some of them having eggs in the 

 incubatory pouch. 



Genus Halia, n. g. 



Ciana, Goodsir. 



Carapace elongate, compressed, covering the thorax, except 

 the three posterior segments. The four posterior legs of the 



