G. C. Crick — Zieten's Ti/pes of Ammonites. 5 



Sowerby's description of his species is as follows : — 



" Globose, umbilicated, septa numerous, much bent in the middle, 

 truncated and not recurved at the ends ; siphuncle central ; umbilicus 

 small ; aperture above twice as wide as long, 



" The length of the aperture is 1^ inch, the width 2| inches." 



In regard to the angle of the septa on the ventral or peripheral 

 area, the presence of obscure coarse costse, and the general form of 

 the shell, the original of Sowerby's fig. 5a agrees exactly with the 

 type of Foord's E. costatum ; the costaj appear to be almost wanting 

 on the earlier portion of the outer whorl, but the fossil is here 

 somewhat imperfectly preserved. 



The specimen represented in Sowerby's fig. 56 is a fragment of 

 an apparently smooth shell, the septa of which form an angle on the 

 ventral or peripheral area corresponding almost exactly to that in 

 the specimen figured by Dr. Foord as E. cUtellarium. It appears, 

 however, to have belonged to a rather more rapidly expanding shell 

 with slightly more depressed whorls than the fossil which Dr. Foord 

 has figured and referred to that species ; in fact, in these respects it 

 agrees better with the earlier portion of the outer whorl of the 

 original of Sowerby's fig. 5a. Still, the form of the septa and the 

 apparent smoothness of the shell lead us to regard the specimen as 

 specifically identical with the example figured by Dr. Foord as 

 j&'. cUtellarium, J. de C. Sowerby, sp. 



As we have not seen the original of Sowerby's fig. 5, we can 

 make no observations on that specimen. 



From the foregoing remarks it will be seen that the specimens 

 figured by Sowerby probably belong to at least two distinct species ; 

 the original of his fig. 56 agreeing with Foord's interpretation of 

 E. cUtellarium, whilst the specimen represented in his fig. 5a is 

 specifically identical with Foord's E. costatum. It would then be 

 of great interest to know where the fossil represented in Sowerby's 

 fig. 5 is, and to learn whether its characters correspond to those of 

 the original of that author's fig. 56, or to those of the example 

 depicted in his fig. 5a, for if it be specifically distinct from the 

 fossil represented in his fig. 5a {= E. costatum, Foord), we think it 

 should, owing to the fragmentary nature of the original of his fig. 56, 

 be regarded as the type of Sowerby's species {E. cUtellarium). 



VII.— Note on Zieten's Type-Specimens of Ammonites polyqonius 



ANB Ammonites discoides. 



By G. C. Crick, F.G.S., of the British Museum (Natural History). 



THE presence of Zieten's type-specimen of Ammonites calcar^ in 

 the British Museum (Natural History) among some fossils 

 which were bought of Dr. Bruckmann naturally suggested an 

 examination of the other fossil Cephalopoda obtained from the 

 same source, in the hope of finding other type-specimens. Thus far, 

 the result of this examination has been the discovery of two more 



1 See Geol. Mag., December, 1899, p. 554. 



DECADE IV. VOL. VII. NO. XII. 36 



