126 A Synopsis of the Recent British Oslracoda. 



knowledge of its anatomy, be certainly classed under any 

 other head ; the overlapping right valve precludes the notion 

 of its belonging to Paradoxosioma, with which, in other 

 respects, it shows considerable agreement. I therefore retain 

 for it the name Cytherideis. This species is described by Dr. 

 Baird as Oy there flavida, Miiller ; but the two are most probably 

 quite distinct : the latter species appears to be a yellow variety 

 of Paradoxostoma variabile. 



Scleeochilus, G. 0. Sars. — Antennas robust, the lower 

 larger than the upper; flagellum long and very slender; poison 

 glands large and many-lobed; mouth produced, conical; 

 labrum strongly toothed; mandible small; terminal lobes of 

 the first pair of jaws"partially wanting*; branchial plate narrow, 

 almost lanceolate; feet short and robust, the first pair having 

 a strong spine at the apex of the basal joint ; post-abdominal 

 lobes very large ; valves elongated, hard, especially at the 

 edges ; surface smooth and shining. 



8. contortus (Norman) . — This species shows, in the struc- 

 ture of the mouth and mandibles, a state intermediate between 

 the typical Cytheridas and Paradoxostoma. 



Pakadoxostoma (Fischer). — Upper antennas exceedingly 

 slender, six-jointed and shortly setose ; lower shorter and more 

 robust, five-jointed, flagellum very large and stout ; poison 

 glands large, lobulated ; mouth suctorial ; labrum and labium 

 forming together a large and stout subcorneal process, project- 

 ing downwards, and terminating in a disk, in the middle of 

 which the orifice of the mouth is situated. Mandibles very 

 slender, protractile, styhform; palp very slender, and without a 

 branchial appendage. Terminal lobes of the first maxillaa very 

 narrow, two lower setse of the branchial plate deflexed. Feet 

 short and robust, last joint elongated, terminal claws short and 

 curved ; basal joint of the first pair bearing a single strong spine ; 

 one eye ; shell thin and fragile, having no definite structure ; 

 valves subequal, mostly higher in front than behind ; ventral 

 margins emarginate in front, so that when the valves are 

 closed there is left an elongated orifice, through which the 

 suctorial apparatus can be protruded. 



P. variabile (Baird) ; abbreviation, G. 0. Sars; Normani, 

 Brady ; pulcliellum, G. 0. Sars ; obliqiium, G. O. Sars ; Hibcr- 

 nicum, Brady; Sarniense, Brady; ensiforme, Brady; jiexuosum, 

 Brady; arcuatum, Brady. 



The remarkable suctorial mouth of these animals at once 

 separates them from all other genei'a, and even without exami- 

 nation of the internal parts, the shell itself gives evidence as 

 to its affinities by the longitudinal aperture between the two 

 valves on the anterior portion of the ventral surface; this opening, 

 through which the mandibles and mouth can be protruded, is 



