202 PLIOCENE MOLLUSCA. 



lieniarl-fi. — The shell here figured as S. liirsnfit.'^ was obtained by Mr. Bell some 

 years ago at Butley. It belongs to the togatvs group, but differs both in form 

 and sculpture from the specimens represented in PL XXII of the present Memoir 

 under the latter name. One of these (fig. 2) I received from Christiania as typical 

 of that species, and with this the Waldringfield fossil (fig. 1) closely agrees. 

 Other specimens on the same plate (figs. 3, 4, and G), called by Mr. Friele S. cnrtai,, 

 but identified by him with S. togatus, are more or less similar. 



The sculpture of the Butley shell is different, resembling more nearly that of 

 S. hirsutiis as given by Jeffreys and by MM. Dautzenberg and Fischer. On the 

 other hand, a Recent specimen of S. togatus from Stockholm (PI. XXV, fig. 11), 

 which shows the fine clathrated ornamentation of the epidermis in that species 

 together with the characteristic chitinous spines at the points where the spiral 

 ridges intersect the lines of growth, approaches it more nearly in form. I have 

 figured an enlarged representation of this feature (fig. 12), which only shows on 

 the epidermis, magnified 6 diameters. 



I fear that in the absence of the epidermis the identification of our fossil with 

 S. hirsutus cannot be regarded as altogether satisfactory, but I give it provisionally, 

 and with some doubt, under that name. 



VLEUIWTOMIDJE. 



Since Wood's monograph of the Crag Mollusca was written many forms then 

 known as Pleurotoma have been separated from it and grouped under other 

 generic names ; it seems necessary, therefore, to revise his nomenclature in 

 order to bring it more into harmony with that generally adopted at present. 

 Much has been published, moreover, during recent years which makes the correct 

 identification of our Crag Pleurotomidse with the various type forms more easy 

 than formerly. Many species, unknown to Wood, have been obtained from the 

 Crag beds, especially from the prolific pit at Little Oakley, which prove to be closely 

 allied, if not identical, with those from the Miocene or Pliocene deposits of other 

 regions, or with the Recent Mollusca of the Mediterranean. I have therefore 

 continued where necessary, and as a guide to collectors, the method before 

 adopted of figuring for comparison with the Crag fossils, often waterworn or 

 imperfect, some verified and perfect specimens received from various foreign 

 correspondents. A certain number of Wood's identifications may need recon- 

 sideration in the light of our present knowledge, Avliile some of his figures, though 

 the best that could ])e obtained at the time, are not equal in the delineation of the 

 minute details of form and sculpture which separate one species from another, to 



