132 



Shell elongated, of ten to twelve convex whorls, separated by 

 deep sutures. The whorls are ornamented with from ten to fourteen 

 grooves, separated by the same number of threads. These grooves 

 vary in width and depth, and the threads also vary in strength, 

 giving the shell a peculiar appearance, which causes it to be easily 

 distinguished from any others of the genus. The disposition and 

 number of wide- and narrow grooves vary on different individuals. 

 The strongest thread and the widest groove occur about the centre 

 of the whorls on this specimen. The mouth is imbedded in the 

 matrix in the individual examined. 



I have found only one specimen of this species, which occurs at 

 Penton. There are several specimens of it from the Carboniferous 

 Limestone of Settle, in the museums at Cambridge, South Ken- 

 sington, Leeds, and York ; and all these are much larger than the 

 specimens from Penton. Mr. Young has specimens in his collection 

 from the shales of the Lower Limestone Series of Craigenglen, and 

 from the shales of the Upper Limestone Series of Swindridge 

 Muir, which are larger than mine, though not so large as those 

 from Settle. Mr. R. Etheridge, junr., (Quart. Journ. Geol. Soc, 

 Vol. xxxiv., p. 19, PI. ii., fig. 29,) describes a small shell from the 

 Calciferous Sandstone Series of Woodhall, near Edinburgh, which 

 he refers doubtfully to A. striatula De Kon. He states that the 

 ridges and grooves are less than twelve, and that the former are 

 separated by spaces nearer equal than is the case on A. striatula. 



Length, 5 mm.; width of body whorl, about i^ mm. 



Locality — Penton. 



Horizon — Calciferous Sandstone Series. 



AcLisiNA ELONGATA. (Flem.) PI. H., figs. 3, 4, 4<r, \b. 



Turitella elongaia, Fleming, 1828, Brit. Animals, p. 305. 



Shell small, elongated, slender, of thirteen to at least sixteen 

 whorls, which are slightly flattened above and convex below. The 

 whorls are each ornamented with from seven to nine keels, which, 

 on some individuals, are separated by nearly-equal spaces ; the 

 widest space, however, is generally just above the middle of the 

 whorl. Sometimes the two spaces next above are equally-wide ; 



