

RECENT BRITISH OSTRACODA. 



101 



backwards almost in a right line; inferior deeply sinuated in the middle. Outline ai 

 seen from above, snbhexagonal, widest in the middle, sides nearly parallel and tapering 

 equally to each extremity, greatest width equal to half the length. End view subtri- 

 ilar, height much greater than the width, prominently keeled. The central portion 

 of the valves is covered with a thick reddish incrustation, and closely and irregularly 

 pitted; this central elevated portion is surrounded by a broad flattened margin, which is 

 devoid of pittings, but is marked, especially in front, by radiating lines. The two eyes 

 are plainly visible through the shell, forming brilliant black spots. Upper antenna' 

 strongly spinous, last joint shorter than the preceding. Flagelluni of lower antenna 

 very short, scarcely reaching the middle of the penultimate joint. Mandibular p 

 four-jointed, armed with three stout curved plumose seta? as in C. albomaculata A 

 terminal joint slender. Legs short, and nearly equal, terminal claws long and cur\< 

 second joint of last pair not so long as the two following joints, claw not ciliated. Post 

 abdominal lobes terminating in two ciliated setae. Male unknown. 



» 



d 



Length A in. 



&"" 4 2 



M. Nor 



This is a very interesting species, as combining the outward form of a typical Oytkere 

 with the anatomical characters of the group usually classed under Cythereis. The other 

 two intermediate species, C. albomaculata and C. convexa, are somewhat abnormal both 

 in external and internal structure, and might, with some show of reason, have been 

 erected into independent genera between Off there and Ci/thereis; but C. rubida bem 

 outwardly a true Cy there, and anatomically a true Cytherei*, seems conclusively to prove 

 the expediency of amalgamating the two genera. 



9. Cithbbb convexa, Baird. (Plate XXIX. figs. 19-27, and Plate XXXIX. fig. L) 



Cythere emivexa, Baird, Brit. Entora. p. 174, tab. xxi. fig. 3. 



arborescens, Brady, Ann. & Mag. Nat. Hist. 1865, vol. xvi. pi. ix. figs. 5-8. 



tCypridina cicatrices a, Reuss, Haidinger's Abhandl. Band iii. (1850) foL 67, tab. a. hg. *i. 

 Cythere cicatricosa, Bosquet, Entom. fossil, des terr. tertiair. de la Prance, p. 76, tab. m. tig. I* 

 Cythere punctata, Jones, Entom. of Tert. Form. Eng. p. 24, pi. h. figs- 5«-5A. 



British type. Distkib^on : /W-Great Britain, Ireland, Bay of Biscay, Le. ^^JT™^ 

 clay and raised beaches, England, Scotland, and Ireland ; crag, England ; and tertiary , German, and 



Sicily. 



Shell rounded, convex, beaked behind, slightly keeled in front and below ; grea des 

 M* in the middle, e q ual to abont two-thirds o f the lenjh ; *£££*»£ 



than the right, and overlapping --^fj ^^Jthe beak into thre, or 

 nterior margin is rounded, posterror beaked and expanded ^^ ^ ^ 



four squamous spines (figs. 19, 25, 27). Ventral ™]f»') J ,,„„, on „ or t „, 



anterior third, and curved upwards behind, ^^Jgfil* h the middle. 

 f*», which project downwards. Dorsa margin bedd* rche d 

 End view oval, tumid, widest in the middle, pointed above and be o 

 f~m above, oblong oval, widest in the middle, and tnpcnng £ ;^ 

 w "lth equal to half the length. The lunge-processes, with 



to each i I rcmitv 



qua I 



XXVI 



