362 Alhany MiififtDit Becorch. 



africana was later found by Uli'ich in thu Ida shales of Bolivia^ 

 and Eeed finds three more of the American species— O. quichua 

 St. and Dod., (7. c.f. iindvlaia, Conrad and G. cf. acuta, Roemer — 

 in the South African beds. 



Gonularia, africana^ Sharped 

 PI. VII., Figs. i;3, 14, 15. 



Tliese very extraordinary forms of life are represented in the 

 All)any Museum collection by two specimens showing the margins. 

 In both cases the lateral plates are continued upwards and are 

 drawn in at the corners, producing scoop-shaped ends with rounded 

 ornamental striations, which bend upwards and close the greater 

 part of the orifice. This seems to point to the fact that the grow- 

 ing edge w^as thin and flexible, the shell being harder and thicker 

 in the main body. There seems, however, to have been a 

 certain amount of play between the two sides of each lateral plate 

 and at the corners whers the two adjacent plates meet. The blue- 

 black matrix in which the largest specimen is pi-eserved, suggests 

 that it is phosphatic, as in so many cases where thin shelled 

 Conulariafi occur. The nature of the shell, consisting of four pairs 

 of separate plates, reminds one of the l)arnacle shell, with its four 

 to ten pairs of lateralia, more or less completely fused at their 

 sides. In no mollusc is the shell separated into parts tangentially, 

 though in the Chitons and the Cephalopods it is divided longitudi- 

 nally. Suggestions have been made by various authors as to the 

 affinities of this gi'oup ; Neumayr compared them with the 

 Capnlidte*, and Ihering'^ regarded them as ancestral Cephalopods, 

 but the balance of modern views tends to regard them as an 

 aberrant branch of the Gastropods. This classification, however, 

 bi'eaks into the definition of the class Gastropoda, which are 

 molluscs with an undivided mantle, secreting a simple shell, and 



'Neues Jahrbuch, 1,S93, Bell. Bd. VIII., p. 29, PL III., fig. 4. 

 '^Aini. S. A. Museum, 1904, Vol. IV., Pt. VI., pp. 247-249. 

 'Sharpe, Trans. Geol., Ser. 2, Vol. VI 1., p. 214, Pi. XXVII., fig. 13. 

 *Abb. k. k. geol. Reichanstalt, Bd. VII., 1879, heft 5, p. IS. 

 *Die Aptychen. Neues Jahrbuch, 1881, I., p. 88. 



