GONIATITES. 57 



convex dorsal portions of the whorls upon its side. Inclusion about half or 

 three-quarters of the whorl. Side of the whorls rising almost perpendicularly 

 from the flat surface of the whorl below, and then, after turning suddenly through 

 an angle of more than 90°, sloping obliquely and almost flatly to the ventral area, 

 and there bounded by a more or less distinct shallow groove, before again turning 

 suddenly to form the keel or back, which is very wide and perfectly flat. Body- 

 whorl apparently smooth. Inner whorls (as seen within the umbilicus) with 

 numerous coarse radiating ribs. Suture-lines sloping obliquely forward in a 

 concave curve across about seven-eighths of the sides, and then reflexed at a sharp 

 angle backwards to the keel, on which they are invisible in the described specimens. 

 Siphuncle small, in the centre of the flat keel. 



Size. — A large defective specimen, measures about 100 mm, in height and 

 45 mm. in depth ; a smaller but more perfect one is 37 mm. in height and 11 mm. 

 in depth. 



Locality. — "Wolborough. There are four specimens in Mr. Vicary's collection, 

 one of which is very large. To this fossil Mr. Salter had attached a label with 

 the words " Discites (?) new and very fine species like D. planotegas.^' The other 

 three specimens are fragments of similar large shells. In the Torquay Museum 

 (Battersby coll.) is a smaller specimen showing the position of the siphuncle. 

 There is also a specimen in the British Museum, another in the Bristol Museum, 

 and another small but perfect example in the Museum of Practical Geology. 



Bemarlcs. — The present species seems very distinct from any other that occurs 

 in Devonshire. It is well characterised by the broad umbilicus with step -like 

 walls, the obliquely flattened sides, the narrow flat back, which may be almost 

 regarded as a vet-y broad keel, and by the definite ribs seen only on the inner 

 whorls. The grooves running round the sides of the ventral area do not seem a 

 constant character, Mr. Vicary's large specimen having no signs of them ; and 

 probably they vanish with age. 



Affinities. — The English species which most nearly approaches it is G. tran- 

 sitorius, Ph., but this may be at once distinguished by its larger umbilicus and 

 shorter and more convex sides. 



Judging from the Vicary and Battersby specimens, it appears to be the same 

 as the G. planidorsatus, Minister, as given by Geinitz, and to this species I was at 

 first inclined to refer it ; but, after a careful comparison of the English fossils 

 with Miinster's original figure^ by Mr. Roberts and myself, we came to the con- 

 clusion that it could not belong to Miinster's species, which has a smaller umbilicus 

 and a broader and more sharply angled back, and the whorls of which are 

 completely involute. 



Neither does it seem referable to Miinster's G. falcifer,^ which approaches it 



1 1839, Miinster, ' Beitr.,' pt. 1, p. 21, pi. iii, fig. 7. 



2 1840, ibid., pt. 3, p. 106, pi. xvi, fig. 7. 



