SCALA (SPINISCALA) TREVELYANA. 529 



Specific Characters. — Shell conical, rather thin ; whorls convex, disjoined ; 

 ornamented by about 16 narrow and flattened longitudinal ridges, oblique and 

 usually continuous, occasionally varicose, the upper part of them expanding into 

 a small and short spine-like pi-ojection; spire elongate, slender, regularly tapering 

 to a fine point; suture fairly deep; mouth subcircular, angulate above; outer lip 

 thickened by the last rib ; umbilicus and basal ridge wanting. 



Dimensions. — L. 25 mm. B. 8 mm. 



Distribution. — Recent: British coasts from the Land's End to Shetland, the 

 Moray Firth and Berwick to Scarborough ; Cork to Londonderry. West Atlantic, 

 Naples (Cams). Dogger Bank; Christiania fiord, Bergen, Christiansund, 

 Bohuslan, Cattegat. 



Fossil: Estuarine clays : Belfast. Holocene : Portrush. 



Miocene : Piedmont. 



Lower Pliocene : Biot, Piedmont, Grenoa. 



Upper Pliocene : Italy — Piedmont, Bologna, Val d'Era, Cornarc. Sicily — 

 Altavilla, Caltabiano, Messina. 



Pleistocene : Valle Biaia, Ficarazzi, Castroreale. Norway — Tajycs-bmnks, : 

 Christiania. 



Bemarks. — This species, widely diffused as recent, being reported to range from 

 British seas in one direction into Scandinavia and in another to the Mediterranean, 

 has been recorded as fossil from a number of southern localities, especially from 

 the Pliocene and Pleistocene of Italy and Sicily. In Great Britain it occurs in the 

 estuarine clays of Belfast and in the Holocene of Portrush, while Prof. Br^gger 

 has figured a typical example from the post-glacial Tapes-hanks of the Christiania 

 fiord. As to its position as a Crag shell, however, some difference of opinion has 

 existed. In 1848 Wood figured a unique and imperfect specimen from the 

 Newbournian Crag of Sutton, which, having compared it with a recent shell in his 

 collection, he referred to the present species. Prof. Sacco accepts this view, but 

 he distinguishes Wood's Sutton fossil by the varietal name of cragtrevelyana. Up 

 to the present no other specimen of this form has been recognised in the Crag 

 since 1848, so that the existence of the typical 8. trevelijana in our Pliocene deposits 

 must be considered doubtful. 



In his first Supplement of 1872, however, Wood figured another and I think 

 different shell under the present name, which M. de Boury regarded as specifically 

 distinct. It is described in the next paragraph as 8. aldehiana. 



The sub-genus 8piniscala, of which M. de Boury took the Italian 

 S.frondicida as the type, was considered by him to include a group of Scalas turricu- 

 late and generally more or less slender, of moderate size, having an elongate spire, 

 a deep suture, convex and slightly disjoined whorls, numerous ribs, lamelliform 

 and reflexed, the upper part of the latter being somewhat enlarged and spinous, 

 with an imperforate base and without a basal disc. 



