76 



than the latter; striae transverse, fine. (Plate LXXXIX. Figs. 

 7, 7a). 



Rhaphoneis amphiceros^ Ehrb. 

 R. Belgica, Grun. 

 R. fliiminensis, Grun. 

 R. seal arts, Ehrb. 



The deposit is particularly rich in specimens of Rhaphoneis, 

 and these present such variations of structure as to suggest the 

 advisability of decreasing the number of species usually consid- 

 ered as belonging to the genus. 



Rhizosolenia Americana^ Ehrb. 

 R. styliforniis, Brightw. 

 SeepU'oneis Cadttceiis^ Ehrb. 



polygo 



aetinoptych 



fi 



ipieulati 



S, eorona (Ehr.), Grun. 

 S. Hmbata^ Ehrb. Rare. 

 6*. Turris (Grev.), Ralfs, 

 Surirella Febigeriiy Lewis. 

 Terpsinee sp. ? 



Trieeratiiiin Amerieanum^ Ralfs, 

 T. condeeoriim, Brightw. 

 T, Ft se her it, A. S. 



TricerATIUM KaiNII, Schultze, n. sp. 



Valve triangular with concave margins ; striation moniliform. 

 convergent towards the centre and intercepted by three costae 

 equidistant between the rounded angles and the unstriated cen- 

 tre. (Plate LXXXIX. Fig 5). 



T. Marylandicum, Brightw. 

 T. obfAisiim^ Ehrb. 



T. robiistwn, Grev. 



T. semicireuiare, Brightw, ( Eiiodia Brightzvellii^ Ralfs J. (Plate 

 LXXXIX. Figs. 6, 6a). 



T. spinostitn, Bailey. 



T. Sole7ioeeros, Ehrb. Rare. 



T. tessellatitm^ Grev. 



T, totdidaticm, Ehrb. 



In a future paper it is proposed to figure and describe several 

 other n^\w species peculiar to the deposit. 



