the Palteozoic Bivalued Entomostraca. 213 



The other known Silurian Cytherce are : — 



Cy there Bailyana, J. & H. \ 



— — - Jukesiana, J. & H. / From the Caradoc beds of 



Harknessiana, J. & H. / Kildare &c, Ann. N. H. ser.4. 



Wnghtiana, J. & H. vol. ii. pp. 54-62 (1868). 



Aldensis, M'Coy. ] 



'? siliqua, Jones. From the Trenton Limestone of 



( lanada, described as a Cytheropsis (Ann. N. H. ser. 3. vol. i. 

 p. 249, pi. 10. fig. 6). 



Other so-called Cytherce and Cytherinai from Silurian rocks, 

 such as C. sublcevis, Shumard, C. alata, De Verneuil, C. sub- 

 recta, Geinitz (not Portlock), and C. cylindrica, Hali, belong 

 probably to Leperditice and cognate genera. 



Bairdia Phillvpsiana } sp. nov. PL XIV. figs. 7 «, b } c. 



Carapace subfalciform, with obliquely rounded, tapering, 

 almost equal ends, highly arched back, and faintly incurved 

 ventral border. The left valve very much overlaps the other, 

 especially on the dorsal edge. Profile acute-oval. 



This almost symmetrical Bairdia (in lateral aspect not un- 

 like the recent British B. fulva, described by Mr. G. S. Brady 

 in his " Monograph of the Eecent British Ostracoda," Trans. 

 Linn. Soc. vol. xxvi. p. 474, pi. 28. fig. 21) is from the Wen- 

 lock Limestone of Croft's Quarry, near West Malvern, but is 

 not common ; and we name it after Prof. John Phillips, F.R.S., 

 avIio years ago shed much light on the geology and fossils of 

 the Malvern district. 



A very similar form to this (and probably identical) occurs 

 in a piece of a drifted Scandinavian block of Silurian Limestone 

 from near Breslau. 



The other Silurian Bairdice are — Bairdia March isoniana, 

 B. Griffith iana, and B. Salter iana, from the Caradoc beds of 

 Kildare, described by us in Ann. N. H. ser. 4. vol. ii. p. 58 

 (1868), and Bairdia protr -acta, Eichwald, Leth. Rossica, livr. 

 vii. (1866,) p. 1338, pi. 52. fig. 19, from the Coral-limestone 

 (Upper-Silurian) of Kamenetz-Podolsk. 



Thlipsuea*, gen. nov. 



A Cytheroid carapace, indented on its anterior third by a 

 variable and evanescent pit, and posteriorly by a deeper and 

 permanent depression, characterizes the Silurian specimens 

 which we have to place by themselves in this new generic group. 



* So called in allusion to the compression of the posterior extremity : 

 8\i\l/is, pressure, aud oipa, tail. 



