







RECENT BRITISH OSTRACODA. 



121 



The excessively rugged surface of the shell would, indeed, constitute a serious impedi- 

 ment to any rapid movement through the water; consequently we do not obscrfe any 

 such condition of carapace in the genus Cypris, nor even in Cc/idona. The two or 

 three specimens on which the species was originally founded are all that have as y<-i 

 been observed. It may be noted that specimens of Ci/pris gibba sometimes assume :i 

 tuberculated or spinous surface ; but never, so far as I know, to such an extent as in 

 the present species. 



Genus 3. Cytheridea, Bosquet. 



Shell, as seen from the side, subtriangular or triangularly ovate, highest at the anterior 

 third; thick and compact in structure. Surface more or less pitted, sometimes smooth 

 and papillose, or concentrically rugose. Hinge-margin of the right val\ e bearing a Beries 

 of small tubercles or crenulations, which are received into corresponding depressions oJ 

 the opposite (left) valve; these tubercles are mostly disposed in two terminal group 



intervening portion of the valve-margin being plain or marked by minute tubercles on 



the left, and corresponding fossae on the right valve. Lucid spots about four, in a trans 

 verse row, near the centre of the valve, and two detached spots (which sometin* 

 coalesce) in front of the main group. Upper antennae very robust, mostly fire-jointed 

 and bearing strong spines; the last joint narrow and elongated; lower antennae torn 

 jointed; urticatus setae lon<? and slender, Particulate. Mandibles large and numerously 



■JD ~^"*~ -~^D 



toothed; palp three-jointed, and hearing a distinct branchial appendage. The right foot 

 of the first and second pairs in the male different from the rest, that of the first pair 

 very strong and prehensile; of the second very feeble, the apical portion rudimentary 



and destitute of a terminal claw. Eyes distinct. 



I am unable to find any good distinctive characters to separate the genua Cypnde,, 

 (Jones) from Cytheridea. G. 0. Sars restricts the latter genus (apparently) to certain 

 very broad and dentate forms, which, however, do not appear to me to preset any w,l- 

 marked generic characters : the animal is not known, but may be supposed to be, m all 

 probability, not far different from that of the typical Cytheridea (Cypnde*^) It 

 may be noted that some of the species included by Sars under Cypndex » ~ - 



tinctly to the series included by Bosquet in his Cytheridea; and one of them (<£* 



belong di^ 



SaMU, Sars) is, as I believe, identical with CytherUUa papulosa Bosquet the «^- 

 tineW „f L t» _, be maintained, the name Cipnd*. should, I think, be res, n cd 



of the two genera be mam 



unless 01 xne two genera, ue uiaiuiouxuu, . ., +„™,r ar.,1 ™«nhqlilv 



delusively for C. to'rosa, which differs *-"^E^£S^ 

 a* mode of reproduction. Many o the ^"^ J^ rf ^ ci , s> 

 Wong undoubtedly to Cytheridea. The genu. is a small on , ^ ( 



though local, occur in prodigious quantities when the conai 



favourabl 



,™ i wvTTT fi^s 13-16, and Plate XL. fig. 6.) 



1. Cytheridea elongata, Brady. (Plate XXVIII. n D s. 



Cohere anyustata, Baird, Brit. Entom. p. 17* tab. **■ H- * ^/-Glacial depusi. 



Atlantic type, ton,,™ : Ite»/-Great Bntam, Ireland, Bay of B»». 



and raised beaches, Scotland and Ireland. ^ . q ^ 



Carapace, as seen from the side, elongate, not much b. ne 



