







RECENT BRITISH OSTRACODA 



437 



Northumberland and Durham coasts, 25-46 fathoms [G. S. B.) ; Ormeshead and Shetland (Mr. D. 

 Robertson) ; Hebrides, 45-60 fathoms (Mr. J. G. Jeffreys). 



This is a strictly deep-water species, and, though occurring over a wide range of coast- 

 line, is seldom found in great numbers. The only locality in which I have found it hi 

 all common is Birterbuy Bay, Ireland, where it is mostly of a deep-brown or daU -blue 

 colour. 



Genus 7. Xestoleberis, G. 0. Sars. 



Shell very smooth and polished, ornamented with small round distant papillae, much 

 lower in front than behind, in the female very tumid behind. Hinge-joint formed by a 

 dentated projecting crest of the left, which is received into an excavation of the right 

 valve. Ventral margin of both valves incurved in front of the middle. Upper antennae 

 six-jointed, the last four joints successively decreasing in length, and bearing very short 

 simple setae; lower antennae short, four-jointed, flagellum of moderate length. Mandi- 

 bular palp four-jointed; "branchial appendage small and bearing only two seta."' 

 Maxillae as in the preceding genus. Feet short. Postabdominal lobes bearing two Bete. 

 Eyes distinct. Ova and immature young borne within the shell of the female. 



This genus is chiefly distinguished by the peculiar form of the carapace, which is very 

 low and pointed in front, elevated and tumid behind, in these respects offering a direct 

 contrast to the genus Eucy there, with which, however, in the character of the hinge- 

 joint and of the surface-markings, it to a great extent agrees. Zenker and Sars agree in 

 stating these animals to be viviparous, a character which I have not myself had an op- 

 portunity of examining. 



1. Xestoleberis aurantia (Baird). (Plate XXVII. figs. 34-37, and Plate XXX FX 



fig. 6 



Cytk 



143. t. v. 6s. 26 (1835), and 



% 8. 



Crust, ex. ord. trib. p. 169, tab. xix. figs. 6-7. 



»»»*uu, -uuijeuorg, ue urusi. ex. oru. inu. p. j.w, «■<*"• a,a - "©"• - ■ 



viridis, Zenker, Anat.-syst. Studieu iiber die Krcbst. p. 86, tab. v. A. 

 Xestoleberis niiida, G. O. Sars, loc. cit. p. 67. 

 Atlantic type. Distribution- : Recent— Norway, Great Britain, Ireland. 



Carapace of thefemale, seen from the side, subjugular ; greatest height a litt le behind 

 ^e middle, equal to nearly two-thirds of the length. Anterior margin much narrowed 

 «*nded ; posterior very broadly rounded ; superior boldly arched, sloping more steeply 

 ln front than behind; inferior slightly sinuated in front of the middle. - '-- -~" 

 *om above, ovate, tapering gradually to a point in ^^^^ 

 latest width behind the middle, equal to half the length. Tin shell ot 



Outline 



fig. 35) differs in being more elongated and scarcely so tumid behind 

 a »* polished, bearing ve^ small scattered papilla. Colour ^^^JT^ 

 Retimes white \ a very conspicuous black or ^P-imson^t m -oHJe, 

 Second joint of the upper antenna* shorter than the three folio* 



ooth 



the 



terminal claws ol 



fla 



er antenna, sh^rt, scarcely more than double the length of the last joint yU , urn 

 r~,w ^._, ,.„ "Lj a^1 v floured. Second joint of the last pair ot 



stou t; poison-gland very large and deeply coloured 



