RECENT BRITISH OSTRACODA. 



425 



a pitted surface, often without papillae (both rules, however, being liable to occasional 

 exceptions) : in C. punctillata we see a mixture of these two characters. 



Bairdia hebertimia, Bosquet, and B. punctatella, Bosquet, are both nearly allied to 

 the present species, but not absolutely identical with it. M. Bosquet, to whom I have 

 submitted specimens, agrees with me in this determination. Beuss's Cytherina inter- 

 media comes, perhaps, still nearer ; but his figures are insufficient for the purpose of 

 identification. Cytlieridea Mfdlen, Bosquet, is also a very near relative, but is separated 

 by the constant tendency to dentation of the anterior, and sometimes of the posterior 

 margin ; this character is entirely absent in C. punctillata. 



The only British locality in which this species has been found abundantly is Loch 

 Eyne, where, as previously stated, it occurs in great numbers in company with C. papillosa. 

 It is by far the most abundant species in the Scotch glacial clays. 



4. Cytheuidea torosa (Jones). (Plate XXVIII. figs. 7-12, and Plate XXXIX. fig. 5.) 

 Candona torosa, Jones, Ann. & Mag. Nat. Hist. ser. 2, 1850, vi. p. 27, pi. 3. fig. 6. 



Qyprideis torosa, Jones (in part), Tertiary Entom. of England, 1856, p. 21; Brady, Ann. & Mag. Nat. 

 Hist. vol. xiii. (1864) p. 62, pi. iv. figs. 11-23, and Trans. Tyneside Nat. Field Club, vol. vi. p. 108, 

 pi. iii. figs. 11-23; G. O. Sars, loc. cit. p. 51. , 



British type. Distribution : Recent — Norway, Great Britain, Ireland, Levant, Sea of Azoff. Fossil — 

 Posttertiary, England and Scotland. 



Shell of female, as seen from the side, oblong, subovate ; length scarcely equal to 

 twice the height. Dorsal margin arched, highest in front of the middle, where it is 

 slightly gibbous. Ventral margin straight, or slightly incurved at the anterior third, 

 mostly furnished with a single stout spine at the posterior angle. Extremities well 

 rounded. The outline, as seen from above, is oblong-ovate (often irregularly and obso- 

 letely angular), sides nearly parallel, extremities obtusely pointed ; the line of junction 

 of the hinge-margins depressed behind the middle, forming a longitudinal sulcus. End 

 view very broadly oval, nearly circular. The right valve is smaller than the left, and 

 has the dorsal margin inclined more steeply, and almost in a right line, from before 

 backwards. Shell of the male elongated, more than twice as long as high. Surface of the 

 valves marked with closely set rounded pittings, and with a more or less conspicuous trans- 

 verse sulcus somewhat in front of the centre. Young specimens are sometimes furnished 

 also with a few short, thinly scattered hairs, and at the postero-inferior angle, near the 

 spine before mentioned, there is often a conspicuous group of rather long hairs. Lucid 

 spots arranged in a transverse row of about four near the sulcus, with two isolated and 

 widely separated spots considerably in advance of the main group (fig. 11). The hinge- 

 ment does not differ materially from that of the two preceding species (see fig. 12). 

 Colour dull brown. Eyes distinct. The penultimate joint of the superior antenna 

 scarcely longer than the preceding ; the last joint rather longer and slender, ending in 

 three setae ; spines long and slender. Terminal claws of the lower antennae very long. 

 Branchial appendage of the mandible-palp bearing five setae (fig. ^p, Plate XXXIX.). 

 La.st three joints of the first foot about equal in length to the preceding one ; second 

 joint of the last foot much longer than the following two, and bearing at its apex one 



VOL. XXVI. 3 M 



