RECENT BRITISH OSTRACODA. 



» 



Genus 13. Sclerochilus, G. 0. Sars. 



Valves elongated, very hard, especially towards the margins; surface smooth and 



shining, ornamented with very minute scattered papillae. Hinge-joint formed by a pro- 



I jecting median crest of the left valve. Antennae robust; second joint of the upper 



bearing a seta on the anterior and posterior margins, the last live joints quickly 

 ' decreasing in size and bearing "numerous long setae; lower antenna larger than the 

 upper, 5-jointed; flagellum long and very slender. Poison-glands very large, and 

 divided into many lobes. Mouth produced, conical; lahrum strongly toothed 31 n- 

 dibles small; teeth numerous and acuminate; palp narrow, indistinctly 3-jointed, with 

 a distinct branchial appendage. Terminal lobes of the first pair of jaws partly wanting ; 

 branchial plate narrow, almost lanceolate, and set with numerous setae on the outer and 

 inner margins. Feet short and robust; second and third joints armed in front with a 











short seta; first pair armed with a single strong spine at the apex of the basal joint 

 Postabdominal lobes larger than usual, forming broad bilobed laminae, and bearing five 



setae. Eye single. 



In outward appearance the one species belonging to this genus is scarcely separabl 

 from the following (Paradoxostoma) ; but the structure of the animal shows an apparent 

 transition from the Cy there type to that of Paradoxostoma. This is more especially 

 evident in the mandibles and mouth. 



Scleroctous contortus, Norman. (Plate XXXIV. figs. 5-10, and Plate XLI. fi 



Cythere contorta, Norman, Ann. & Mag. Nat. Hist. vol. ix. 1862, p. 48, pL B. «* 15; and Trans, 'i yn.- 



side Nat. Field Club, vol. v. p. 150, pi. iii. fig. 15. 

 Sclerochilus contortus, G. O. Sars, loc. cit. p. 90. 



t» ,r p;<, M v Fn<s<til — Glacial and nu«u 



British type. Distribution : Jfec«*-Britain, Norway, Bay of Biscaj . tossii 

 beaches, Scotland, Ireland, Norway. 



Carapace of t^ female, seen from the side, elongated, bean-sbaped, >»£>£** ^ 

 in front ; greatest "height rather behind the middle, and equal to eons dera h J a 

 half the length. Anterior and posterior maH~ — ** : superior boldly ar, bed, 



doping steeply in front, inferior deeply sinuated in front, convex in ■ 

 seen from above, compressed oval, more than twice as long as mow , - 

 behind the middle, tapering to the extremities, the anterior of which m £ 



idth 



Shell sm 



pointed. Shell of the male more elongated, the dorsal margin ess < ^ 



and polished, very sparingly punctate, the »«£• |«*- * . 



bating stri*. Colour yellowish, ™*^f"™S*>*<*»» ™* Ao * r 



spots five, linear-ohlomr. naraUel. Third joint ol tlie uppe „ 



y - u, c , miear-ooioi, S , paiauc. — . ' f y three following. " J*ancm 



the preceding, and about equal to the united lengths o ^ . ^ ^ rfjB 



appendage of the mandibular palp bearing four lon D , s ^1 ^ terminate d by a hooV 

 having only two terminal lobes, one of which is very m , • ^ ^ following. Ba> 

 spine. Second joint of the last pair of feet shorter ^^ ^^ ^ 



Portion of the male copulative organ s semiovate ; uppe ^ 



arch ; distal portion smaller, subovate, nairowea 



s 



^gth & in. 





