11. INVERTEBRATA. 



CEPHALOPODA. 



(See ante, p. 18.) 



Belemnites (Actinocamax) pistilliformis, Blainville, Memoir sur 



les Belemnites, p. 98, pi. v. figs. 14 and 15, 1827. 



[Not B. pistilliformis, Sby. Min. Con. 1828.] 

 „ jaculum, Phillips, Geol. Yorkshire, I. pi. iii. fig. 1. 



„ pistilliformis, Duval, Journ. Belem. des Terr. Cret. 



infr. de Gastellano, pi. 8, figs. 10 — 16. 

 „ Ewaldi, Strombeck, Deutsches Geolog. Gesell. 1861, 



p. 34. 

 „ pistilliformis, Ooster, Pet. des Alpes, i. Cephalopoda, 



pi. 2, figs. 9—11, p. 21. 

 „ pistilliformis, Renevier, Terr. Neocomian des Voirons, j 



pi. 1, figs. 1 — 4, p. 5. 

 [Belemnites subfusiformis, auctorum is a variety of this species. 



See infra.] 



This species belongs to a group of Belemnites characterised by 

 the soft and powdery nature of the alveolar region of the guard, 

 so that commonly this part is not preserved. Further, in con- , 

 sequence of the outer layer being more friable than the inner, a 

 delamination occurs in successive coats — * en lames en retrait.' A 

 perfectly fusiform structure is thus produced, being a guard, 

 wanting its alveolar portion and its phragmocone. The Genus 

 Actinocamax (Miller and Voltz) was erroneously grounded upon 

 specimens in this condition, and the name has consequently been 

 rejected. Dr Schluter has, however, lately revived the name, and 

 I think it may be retained with advantage to denote a well- 

 marked group of Cretaceous Belemnites, including Belemnites 

 pistilliformis, subfusiformis, minimus, attenuatus, ultimus, and 



