ALBIAN FOSSILS DISCOVERED AT OKEFORD FITZPAINE. 95 



This appears to differ from d'Orbigny's species (T. simplex) by 

 being more compressed, having a greater height, and in its less 

 oblique postero-dorsal margin. It corresponds very well with an 

 undescribed form from Black Ven, hear Lyme Regis, specimens of 

 which are in British Museum. 



No accurate dimensions of this shell can be given on account of 

 its being so much buried in the matrix. 



TRIGONIA ALIFORMIS, Parkinson. 

 PI. iii., fig. 14. 



Trigonia aliformis, Parkinson : Organic Remains, 1811, Vol. 3, 

 PI. 12, fig. 9, p. 176. J. Sowerby : Mineral Conchology, 1818, 

 Vol 3, pi. 215, p. 27. Lycett : Mon. Palseontographical Soc., 

 1875, pi. 25, figs. 3-6, p. 116. 



A very imperfect example of this species is in the collection 

 associated with a specimen of Syncyclonema orbicularis. It is a 

 left valve with a much inflated anterior area ; posteriorly depressed 

 and attenuated. The umbo is elevated, incurved, and recurved ; 

 the posterior area has a plain and curved inner border, the outer 

 border being ornamented with transverse costellse (the intermediate 

 transverse striations of the area are absent in our specimen) ; the 

 pallial costse originating at the areal border are rounded, closely 

 arranged posteriorly, and in well-preserved examples should have 

 crenulated edges. The species is mainly characterised bv its 

 posterior depression and attenuation, and by the narrow, inflated 

 condition of the anterior half of the shell. 



Dimensions Height = 15 ) 



. Millimetres. 

 Length = 2o ) 



According to Mr. Lycett's investigations no true form of this 

 species had been collected in foreign localities, notwithstanding the 

 researches of Orbigny, Goldfuss, Pictet and Roux, &c., and Lycett 

 states "that the few figures given by foreign authors which are 

 correctly attributed to that species (T. alijormis) are delineations 

 of British specimens." 



RANGE OF SPECIES. Albian. 



LOCALITIES. Blackdown and Haldon. 



