322 



MISS MCDONALD A:N^D DR. TRUEMAN OX [vol. IxxVli, 



Fiff. 12. 



.^. ^-. -Procerithium cf. 

 tenuiornatum x 5. 



features that we emphasized in developmeDt, and to the flattish 

 whorls. It would seem that JP . foveolatum differs frona P. tenui- 

 ornatum in possessing a greater number of spirals at all stages of 

 development, and in the coarser axial ornament in the adult. 



These two species obviously belong to another division of the 



Procerithida^, separate from all 

 those considered previously ; the 

 existence of the bicarinate young 

 is reflected in the bicarinate stages 

 in some species just considered, but 

 in P. tenuiornatum and P. foveo- 

 latum it is retained to a later 

 stage : that is, until some time after 

 the axials have appeared. 



These forms evidently belong, 

 therefore, to a somewhat more 

 primitive group than those that 

 we have been considering, which 

 have a prominent three-spiralled 

 stage. This latter type is, how- 

 ever, illustrated by a specimen 

 (fig. 12) from the Lower Lias 

 {jamesoni zone), from the railway- 

 cutting at Toddington, near Winch- 

 combe, Gloucester (L. Richardson 

 coll. L.Gr. 51), which closely re- 

 sembles P. tenuiornatum in form 

 and ornamentation, but differs in 

 that, by the sixth wdiorl, three 

 it probably represents a type more 

 advanced than P. tenuiornatum. 



P^Locality and horizo n . — The holotype is a specimen from the 

 Lower Lias {armatus zone) of Folh^ Lane, Cheltenham. 



rows of nodules are present 



(B) Cerithinella Gremmellaro, emend. Cossmann. 



Elongated shells, whorls almost flat, spiral angle low, aperture 

 quadrangular ; ornamentation : spiral lines crossed by twisted axials, 

 producing tubercles arranged in groups or bands, often near the 

 suture. 



Cerithinella cf. co:;iErsA (Tate). (Text-fig. 13, p. 323.) 



Ceritliium confusum Tate (23, p. 205). 



Ceritliium {CerWiinella ?) confusum Wilson & Crick (28, p. 301 & pi. ix, 



figs. 2-2 a). 

 Cf. Ceritldnella ? terehellopsis Cossmann (3, pi. vi, figs. 4-5). 



Dimensions of our specimen (estimated). 



Xiength. Breadth. Length of spire. 



20 mm. 20 per cent. 80 per cent. 



Spiral 



Sutiiral 



angle. 



angle. 



12° 



100° 



