45 



figures. On the other hand, close, thi-ead-Hke strias, simihir to those 

 which are so characteristic of A. Jilicinctus, are shown in Tietze's illus- 

 trations of A. quadrisulcatus, although nothing is said about them in the 

 text. Zittel says there are never more than four transverse grooves 

 to each whorl of A. quadrisulcatus, but Tietze figures a variety with five. 

 In a large though distorted specimen of A.filicinctus, there are at least 

 sixteen grooves or constrictions on the outer whorl, in the inner ones 

 even they are often veiy numerous. By this latter character A.fili- 

 cinctus may be readily distinguished from D'Orbigny's species. 



The aperture of the original of Plate II., figs. 2a and 2b, presents an 

 appearance which gave rise to a curious mistake. It is almost filled with 

 small white crystals of calcite, but in the centre of the inner margin of 

 the whorl there is a dark coloured ring, (like the rough end of a tube) 

 and this was at first thought to be the siphuncle. On making a transverse 

 section of the shell, at nearly a right angle to the mouth, a similar 

 appearance was seen in one part of the surface exposed. On a careful 

 re-examination of the specimen with a lens, traces of the true sij^huncle 

 were found in the ordinary position on the periphery, and the illusive 

 nature of the other was then apparent. It would have been su2:)erfluous 

 to mention this circumstance, but as figure 2b (on Plate II.) might 

 otherwise mislead, it is as well to state that it was intended to represent 

 the appearance presented by a section of the original of figure 2, with 

 special reference to the position of the supposed siphuncle. In this 

 figure, what seem to be the outlines of the inner whorls, as well as the 

 presumed siphuncle, (which by accident is placed a little too high up) 

 arc caused by adventitious matter in the interior of the shell. 



Ajimonites Cuenocostatus. (Provisional name.) 



Plate IX., figs, 2, 2a. 



(Perhaps a half -grown specimen of A. (Lytoceras) Liebhjl, Oppel. 

 Compare Zittel's Cephalopoden der Stramberger Schichten," especially Plate IX., 

 figures 6a, 66 and 6c.) 



Shell com^josed of many loosely coiled, and scarcely involute, rounded 

 whorls, whose convex surface is encircled by numerous fine, transverse 

 and minutely crenate raised lines. 



Volutions about five or six, nearly circular in outline, but a little 

 compressed at the sides, and then sloping rather suddenly inwards and 

 downwards to the sutiu-es, which are very deeply excavated ; periphery 



