A FresJnvafcr Bed at the Base of tJie L. Carboniferous. 291 



Description of Fauna. 

 Vivipanis carhonarius sp. nov. PI. XIII, Figs. 1 and 2 

 Descrii^tion. — Height of largest specimen . . 14 mm. 

 Height of body whorl . . . 6-5 mm. 



Body whorl to^ total height . . 46 : 100 

 Spiral angle ..... 50° 

 Sutural angle ..... about 100° 

 Shell thin, smooth, turbinate, umbilical furrow obscure. Number 

 of whorls 4-5 ; whorls tumid, separated by a deep suture ; sutural 

 angle only moderately oblique. Apex blunt. Ornament consisting 

 only of fine growth-lines becoming rugose on the body whorl. Mouth 

 apparently sub-circular, but obscured by crushing. 



The oldest British example of Viviparus {Paludina) so far recorded 

 is P. langtonensis Hudleston, from the Paludina bed in the Chipping 

 Norton limestone of Inferior Oolite age at Langton Bridge, where it 

 is associated with other freshwater species and occasionally seeds of 

 Chara, etc. Viviparus carhonarius differs from P. langtonensis in 

 its relative proj^ortions as will be seen by a comparison with the 

 measurements and description of the Inferior Oolite species,^ 

 F. carhonarius being a distinctly blunter and more tumid form. 



Carhonicola angulata, de Ryclcholt. Pi. XIII, Fig. 3. 



Numerous specimens of a thin-shelled lamellibranch, evidently 

 a Carhonicola, and apparently referable to de Ryckholt's species 

 C. angulata, occur with Viviparus carhonarius.^ 



Euomphalus sp. 



A few crushed specim^ens of gastropod shells, most nearly 

 resembling Euomphalus, also occur. 



The only other organism met with in this bed was a crushed and 

 fragmentary specimen of a Pleurotomaria, which occurred on the 

 upper surface of the deposit and was probably introduced at the 

 beginnmg of the marine submergence which followed. 



The specimens of F. carhonarvas occurred in considerable numbers 

 and include numerous young forms, and the same was the case with 

 the specimens of C. angulata. In comparing this occurrence of 

 Viviparus with the oldest previously loiown species in the Inferior 

 Oolite, it is interesting to note that the Horton bed is also overlain 

 by a baild containing fish remains and plants, marking m both cases 

 the incursion of the sea to form an estuarme deposit. Outside of 

 Britain the oldest recorded species of Viviparus also occurs m the 

 Lower Oolite (Bathonian) of France. Hitherto the accepted opinion 

 appears to have been that freshwater gastropods made their earliest 

 appearance in Mesozoic times. Thus Professor SoUas, in his chapter 



^ Inferior Oolite Gastropoda, Mem. Pal. Soc, 1896, PL xliv, figs, la 

 and lb, p. 488. 



- See Hind, Monogr. Carhonicola, etc., 1894-6, pi. xi, figs. 3-5, p. 75. 



