406 Messrs. T. R. Jones and J. W. Kivkby on Miinster's 



cognize specific forms by the Count's very brief notice of a few- 

 features. 



The series of specimens sent us by Herr Giimbel include 

 examples of all the forms described by Count Miinster, besides 

 one which he has not described. Our opinions on the species 

 and their generic relations, as derived from these specimens, are 

 expressed in the following notes. 



1. Leperditia Okeni, Minister, sp. PI. XX. figs. 1-3; 

 var. acuta, fig. 4. 



Cythere Okeni, Miinster, Jahrbuch f. Min. 1830, p. 65, no. 15. 



Cypris Scotoburdigalensis, Ilibbert, Transact. Royal Soc. Edinb. vol. xiii. 



p. 179, figs, a-c, 1836; Portlock, Gcol. Rep. Londonderry, p. 316, 



pi. 24. fig. 13 c, 1843. (Small variety.) 

 Cypris inflata, Murehison, Sil. Syst. p. 84, fig. A, 1839. (Probably a small 



variety, like the last mentioned.) 

 Cypris subrecta, Portlock, ibid. fig. 13 5, 1843. 

 Cytherce arcuate, (fig. 9), cornuta . (fig. 12), elongata (fig. 13), Hibbertii 



(fig. 15), inornata (fig. 18), scutulum (fig. 21), oblonga (fig. 22), spini- 



gera (fig. 23), gibberula (fig. 25), in pi. 23 of M'Coy's ' Synops. Carb. 



Foss. Ireland.' (Probably either varieties or imperfectly drawn small 



specimens of L. Okeni.) 

 Bairdia laevigata, var. nigrescens, D'Eichwald, Lethsea Rossica, p. 1342, 



pi. 52. fig. 5, 1860. 



Length -^— rV inch, height xt— tV inch. 

 ■This is a Leperditia, with the hinged or dorsal border usually 

 a little over half the entire length, and the free or ventral mar- 

 gin boldly rounded and somewhat oblique ; valves either mode- 

 rately convex or strongly gibbous, but always more or less swol- 

 len, and sometimes ridged, at the dorsal region of the left valve, 

 as other Leperditia are ; and either meeting along the ventral 

 margin with a slight flange or with the right strongly over- 

 lapping the left valve ; surface smooth. 



None of our Bavarian specimens show either eye-spot or 

 muscle-spot ; but these are sometimes visible on other specimens. 

 The various sizes of the individuals indicate probably differences 

 of age, habit, and perhaps sex. Fig. 1, PI. XX. may be regarded 

 as the normal subovate form. Pig. 2 is smaller, more oval and 

 obtuse, and rather more gibbous in proportion. Pig. 3 is still 

 smaller, but is like fig. 1 in its proportions. Pig. 4 is small and 

 very acute anteriorly : it is associated in Scotland and elsewhere, 

 as in Bavaria, with the other varieties; we may term it var. 

 acuta. 



L. Okeni is found in Russia* and in Nova Scotiaf, as well as 

 in Germany, Belgium J, and in the Upper and Lower Carboni- 



* As we learn from specimens kindly sent to us by M. E. d'Eichwald. 

 t Dr. Dawson's collection comprises some specimens from Horton, N. S. 

 X Known to us by specimens from M. Bosquet. 



