Mr. C. Spencc Bate on the British DiastylicUc. 459 



thorax without a palpe. Telson rudimentary. Upper antenna 

 prominent, lower membranaeeous. 



Halia trispinosa. PI. XIV. fig. v. 

 Cuma trispinosa, Goodsir. 



The carapaee is long and much compressed, the lateral angles 

 meeting in front of the antennal segments, and projecting for- 

 wards into a rostrum-like point. Half- way between the eye and 

 the posterior margin of the carapace are two (three, Goodsir) 

 small teeth or spines, from which the specific name is derived. 

 The superior antenna consists of a single-jointed peduncle and 

 a terminal tilament, the first two segments of which are half 

 the length of the whole organ ; the remainder are minute and 

 furnished with cilia. The lower antenna consists of a peduncle 

 formed of two minute articulations, calcareous in structure and 

 furnished with plumose cilia, and a terminal filament of a mem- 

 branous structure, soft and flexible in its character, the anterior 

 portion of which exhibits an appearance of rudimentary articu- 

 lations, and the organ generally bears a strong resemblance to 

 that of the embryo Crustacean. 



The mandible (fig. G) is furnished with a very prominent 

 molar tubercle and a secondary incisive denticle, as well as a 

 row of intermediate spinous hairs more or less furnished with 

 cilia. The maxillae (figs. 7, 8) are foliaceous, and resemble those 

 described in DiastyUs. 



The maxilliped (fig. 10) consists of a long and stout basal 

 joint, followed by a second, rather shorter and less robust, fur- 

 nished on the inner margin with minute denticles, and termi- 

 nated by two minute articulations well supplied with cilia. This 

 pair of members carries the branehiffi. 



The first gnathopod (fig. 11) is pediform, consisting of a long 

 basal joint and four or five terminal smaller ones. 



The second gnathopod (fig. 12) is also pediform, but deve- 

 loj)cd so as to fulfil the office of an operculum. The basal joint 

 is long, and the external anterior margin is prominent and fur- 

 nished with a number of hairs ; the second joint is similarly 

 formed, but short ; the three terminal ones are unimportant. The 

 member is furnished with a palpe consisting of a basal joint and 

 a terminal filament. 



The next succeeding leg (PI. XV. v. fig. 13), which is homo- 

 logous with the large cheliform organ in the Decapoda, consists 

 cf a long basal joint (the rest except the palpe in our speci- 

 mens were broken off). 



The four succeeding pairs closely resemble each other, and 

 are each respectively formed of a long basal joint and four or five 



