\.\SSA (HIMA) INCRASSATA. 325 



Finmark to the A/ores, Morocco, Senegal (Locard), Mediterranean, Adriatic, 

 ^Egean, Syria, Egypt. 



. Fossil: English Crag, upper zones, not common. Belgium: 

 Poederlien (Van den Broeck). Wexford, Isle of Man (A. Bell). British 

 Pleistocene : widespread. 



Lower Pliocene : Biot, Roussillon, northern Italy. 



Upper Pliocene: Italy — Valle Andona, Val d'Era, Bologna. 

 Sicily — Altavilla. 



Pleistocene : Sicily — Messina, Monte Pellegrino, Nizzeti. 



Italy — Livorno, Valle Biaia, Reggio, Taranto, Gravina. 

 Christiania fiord, Trondhjem, Uddevalla. 



Remarks. — When the history of the Pliocene epoch comes to be written, 

 particulars as to the occurrence of certain species, or even varieties, at certain 

 localities or horizons, which now seem unimportant, may prove interesting and 

 useful. Much lias been written about the present species, indeed MM. Daut- 

 zenberg and Fischer, in their great work published in 1912 under the auspices 

 of the Prince of Monaco, have given a list of nearly 300 papers, of more or less 

 importance, dealing with the subject. Perhaps I may add a few notes on the 

 distribution, in time or space, of some of the varietal forms which have been 

 grouped under the present specific name. 



In 1882 Bellardi described a fossil from the Italian Pliocene as N. incrassata, 

 recording it from both the Upper and Lower horizons of those deposits. It is 

 more delicate than the common British N. incrassata, with a longer and more 

 slender spire and more convex whorls, but it has the thickened lip characteristic 

 of this species, of which it is considered a variety. I have this form in my 

 collection both from the Lower Pliocene argiles bleues of Bordighera, and the 

 Upper Pliocene deposits of Asti, but I do not know it as recent in British seas. 



The typical British variety is not common in the Crag. It does not occur 

 in the list of mollusca reported by the late Robert Bell and Prof. Kendall from 

 Walton, and I have not met with it during my many years' work at Oakley. 

 It has been found, however, though not commonly, in the later Red Crag and in 

 the Icenian. A thickened form is exceedingly abundant, however, in the Wexford 

 gravels (fig. 8), but it is the northern variety /3 of my p. 88, very common in the 

 Christiania fiord, and apparently the one figured by Profs. Gr. O. Sars and Bro'gger 

 which, so far as my information goes, is more frequently found in the later beds of 

 the Red, and in the Icenian Crag. 



If Nyst's figure of N. incrassata from the Scaldisien of Belgium (op. cit.) is cor- 

 rectly drawn, the shell given by him under that name is possibly a different species. 



M. Van den Broeck does not include it in any of his lists from that horizon, 

 though it is given by him in a later paper from the Poederlien deposits of Antwerp 

 as something new to the Belgian Crag. 



