426 



MR. G. S. BRADY'S MONOGRAPH OF 



long ringed seta and one shorter spine ; terminal claw slender, about equal in length to 

 the second joint. Right foot of the first pair in the male prehensile, four-jointed, much 

 stronger than the left; the apex of the second joint giving origin to a long, curved, 

 bearded seta; terminal claw moderately strong; basal joint of the right foot of the 

 second pair bearing three plumose setse (fig. hg, Plate XXXIX.) ; second joint dilated at 

 the distal extremity and bearing on the anterior margin two fasciculi of short setse, and 

 at the apex one very long ciliated seta ; the left foot of the second pair scarcely different 

 from that of the female. Second joint of the last pair on the right side armed on the 

 anterior margin with a dense brush of setse (fig. 5 A"), on the left side with four semi- 

 verticillate groups of shorter hairs. Abdomen of the female (fig. 5 m) ending in a large, 

 curved, acuminate process ; postabdominal lobes bearing two very small plumose set£e. 

 Copulative organs of the male divided at the apex into two processes, one of which is 

 acutely lanceolate and serrated at the margin, the other obtusely rounded (fig. 5 A;); basal 

 portion very large and subovate. The ova and undeveloped young are carried within 

 the carapace of the female. 



Length ^ in., height 5^ in. . S 

 Hub. In brackish and occasionally in freshwater. Gravesend {Prof. T. R. Jones) ; Girdler Sand, Thames 

 {Mr. ^. C. Davison); Sedgefield, in fresh water; Hartlepool, Weston-super-Mare, and Guernsey 

 {Rev. A. M. Norma7i) ; Belsay, in fresh water; Warkworth, Alnmouth, Camboise, Seaton Sluice^ 

 Jarrow Slake, and in shell-sand from Pegwell Bay {G. S. B.). 



Cytheridea torosa was first found living by Prof. T. Rupert Jones in brackish water at 

 Gravesend, and was by him referred to the genus Candona ; further examination, how- 

 ever, showed the animal to be allied to, if not identical with, Cythere, and revealed also 

 peculiarities of shell-structure for which the genus Cyprideis was proposed. But there 

 seems to be no difference of generic importance between this species and the older genus 

 Cytheridea. The peculiar setse and ringed hairs which I have described as existing in 

 C. torosa (Ann. & Mag. Nat. Hist. loc. cit.) are found in some, if not all, of the Cytheridece 

 and in some allied genera ; and the characters of the first pair of feet in the male are 

 analogous also to those met with in the foregoing species, though the right foot of the 

 second pair is not rudimentary as in those species. Por these reasons I have thought it 

 desirable to class C. torosa as a true Cytheridea, though there remains one important 

 character in which, so far as I know, this species stands alone amongst the Ostracoda, 

 namely, the enormous number of ova borne at a single time by the female. How far this 

 may prove to be of generic importance, future investigations must show ; it is, at any 

 rate, an interesting fact, and one which fully accounts for the immense numbers in which 

 the species is often found. 



I have had the opportunity, through the kindness of Professor T. E-upert Jones, of 

 examining the specimens, both recent and fossil, from which the species was first 

 described ; and I find that the more strongly tuberculated forms, from which it derived 

 its specific name, are referable to C. lacustris. Under these circumstances the name 

 lacustris should, according to the laws of zoological nomenclature, give way to the prior 

 term torosa, and the smoother species (the torosa of Sars, of the present monograph, and of 

 my previous paper) be named afresh. But as the two specific designations here used 



