576 ME. LINSDALL RICHABDSOST ON [Nov. I906, 



complicated by the fact that, associated with indubitable specimens 

 of the species under consideration, are forms differing therefrom 

 either in being very much more erect, or in being very consider- 

 ably thinner but equally straight. It does not seem desirable to 

 separate these forms, at any rate for the present, and provisionally 

 they maybe regarded as varieties, and D. elongatum as the collective 

 species. 



Moore, however, named the form which was erect and of about the 

 same size as Dentalium elongatum, D. gracile ; and it may possibly be 

 convenient to record such specimens under this name. In PI. XLV, 

 fig. 19 a, will be found a figure of Moore's holotype. The specimen 

 came from the armatum-heds of Camerton, and is now preserved 

 in the Bath Museum. Pig. 19 b shows the same enlarged, and 19 c: 

 is a transverse section of the anterior end. Fig. 18 represents a 

 specimen referable to Moore's ' species,' obtained from the armatum- 

 zone exposed in the approach-cutting to the Hunting-Butts tunnel 

 (Gr.W.E.), near Cheltenham. 



The very slender erect form has been noticed at several localities, 

 and is possibly the forerunner of Dentalium filicauda opalina, 

 Quenstedt. It is a little doubtful whether Quenstedt's species 

 should be associated with Dentalium elongatum, Miinster. He said 

 that it was smooth and similarly constructed ; but remarked that 

 * at the top the tube narrows to the thinness of a human hair ' ; 

 and continued, 



' the Denfalia in Lias a. pag. 55 do not become so thin as this, although they 

 have just the same appearance. This genus plays an important part for the 

 first time in the opalimis-nodules, and continues with the same species up to 

 Beta.' ('Der Jura' p. 329.) 



This extreme tenuity is not one of the characteristics of Dentalium 

 elongatum, Miinster, and most probably Quenstedt's form is distinct 

 therefrom. 



The shell which Oppel identified with D. elongatum came from 

 deposits between the zones of Ammonites torulosus and A. ojpalinus, 

 and along with D. filicauda opalina, Quenstedt, can only be pro- 

 visionally associated with Minister's species. Dentalium ParMnsoni, 

 Quenstedt, from the Middle Lias (his Lias S), is probably the same 

 as D. elongatum. 



In the zone of Belemnites acutus at Renwez, Etales, and Aiglemont, 

 Terquem & Piette found D. elongatum very abundant, and attaining 

 a length of from 30 to 40 millimetres. 



Dumortier's specimens from the Infra-Lias, which he referred to 

 this species, are most probably Dentalium etalense, Terq. & Piette ; 

 but those from the margaritatus-'be&s of Mont Ceindre are doubtless 

 correctly namecb 



Balph Tate recorded this scaphopod from the margaritatus-, 

 spinalus-, annulatus-, ai\& jurensis-heds of Yorkshire. The fragment 

 which he figured is preserved in the Museum of Practical Geology 

 [7997], and shows well the fine ' concentric striae.' 



I have examined species of Dentalium elongatum from the beds 



