348 Dr. FiTTON on the Strata below the Chalk. [App. A. 



Fig. 11. Trigonellites latus Parkinson*. ( — Ichthyosiagones problematicus, Dr. Riippellf; 

 Aptychus Icevis, Von MeyerJ.) Oblong, triangular, compressed ; one edge and one angle rounded ; 

 the longest edge flattened ; one surface concave, striated ; the other nearly flat, smooth, but 

 marked with numerous minute circular pits ; tissue cellular. I have just learnt from a specimen 

 lent by Mr. Bean, that fig. 18. in PI. V. of Phillips's Geology of Yorkshire, is a species like 

 this. It is referred by Mr. Phillips to the Oxford clay ; but Mr. Bean observes that he has 

 had the same fossil from the Kimmeridge clay of Shotover Hill. A larger species is found at 

 Scarborough, perhaps the same as that before us. (supra, pp. 273, 292, and 316.) 



Dr. Fitton, by whom the specimens here represented were found, in clay, near Whitchurch 

 in Buckinghamshire, and at Southrey between Cambridge and Ely, (supra, pp. 273, 292, and 

 3 16,) remarks: " When I found this fossil in 1827, I was unacquainted with the publications then 

 " relating to it, and those of Dr. Riippell and Mr. Von Meyer had not appeared ; — but so far as 

 " I can recollect, there was nothing in the circumstances attending these remains that could illus- 

 " trate their origin and connexions. Along with them I found in Buckinghamshire Gryphcea Viv 

 " gula, but no Ammonites : in Cambridgeshire, Ammonites Lamherti is mentioned as occurring 

 *' at the same place (p. 316.). The valves of the fossil, like those of the Gryphaea, at both places 

 " lay in the clay which contained them, as detached shells might be expected to do, if they had 

 " been lodged confusedly in soft mud. Smaller and thinner valves, perhaps of a different species, 

 " accompanied the larger specimens at Whitchurch, Bucks." 



" Of the many names given to this fossil, I have, after some hesitation, retained that of Tri- 

 " gonellites, which indicates no more than form ; the relations of these singular bodies being still 

 " obscure. As the valves are very often found detached, the term may be used provisionally, or 

 " even ultimately remain, as a convenient denomination ; in the same manner as Belemnites con- 

 " tinues to be employed, although the bodies to which that appellation is given, are no more than 

 " subordinate portions of some complex structure." 



" If the fossils represented in Plate XXIII. be truly of the same species with those of Solen- 

 "hofen, their identity is deserving of notice, geologically." 



Fig. 12. Nerinea Goodhallii. Turrited, smooth; whorls numerous, half as long as they are 

 wide, concave. There are three plaits in the interior, one upon the columella, one opposite to it, 

 and one above it within the whorl ; aperture rhomboidal. The section represented in the left 

 hand figure shows the generic character. The same species but much larger, is found in the Bou- 



* " Organic Remains &c.," vol. iii. Plate XIII. fig. 9. and 12. 



t Abhildung und beschreibung einiger neuen oder wenig gekannten Verstemerung, aus den 

 Kalkschiefer Formation von Solenhofon: von Dr. Ed. Riippell, — 4to, Frankfurt, 1829. Since this 

 sheet has been at the press, (July 1836,) a short paper by Dr. Riippell has appeared in the Lon- 

 don and Edinburgh Philosophical Magazine, (July 1836, vol. ix. p. 32, &c.), to which I wish to 

 refer the reader. Dr. Riippell regards the two species of Parkinson's Trigonellites, as belonging 

 to distinct genera : in one of which (T. lamellosus, P.) he supposes the valves to have formed the 

 opercula of an animal somewhat resembling an Ammonite, but destitute of septa : this he proposes 

 to denominate Pseudammonites. For the second genus, (to which the specimens represented in 

 Plate XXin. appear to belong,) Dr. Riippell retains the name of Ichthyosiagones, originally used 

 by Bourdet ; and in this case the valves appear to have been internal shells, in large elliptic mus- 

 cular masses, the structure of which has not yet been brought to light. Subsequently to the pub- 

 lication of Dr. Riippell's first memoir, Mr. Von Meyer, in a paper referred to below', proposed a 

 different view of the relations of these bodies ; and gave the name oi^ Aptychus to a genus compre- 

 hending all the different forms. 



' Acta Acad. Leop. Carol. Nat. Cur. \o]. ^v. Part 11. Read October, 1829; pp.68 — 12.5. 

 tab. Iviii. fig. 1, 2, 4. 



