S7S PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 4, 



different genera, and applied to Globiconcha characters which do not 

 belong to it. This supposition is strengthened by his placing together 

 shells with a sunk and an elevated spire, which are obviously of dif- 

 ferent species. Unfortunately, M. D'Orbigny's answer in defence of 

 the place assigned to his genus Globiconcha in the family of the 

 Acteonidce, is not sufficiently explicit as to its true generic characters 

 to clear up all doubts respecting it. 



I have been forced to enter into the above details, to explain why 

 I cannot follow M. Desmoulins in uniting to the Globiconchce the 

 species to be here described : a single remark will explain why they 

 should not be placed in the genus Dolium, as proposed by him, 

 namely that they have no canal nor notch to the aperture, and 

 therefore belong to the Phytophagous division of Gasteropoda. 



The callosity inside the mouth has suggested the name Tylostoma 

 for the genus, from tvKos, a callosity, and aroixa, a mouth : it may 

 be thus defined : — 



Tylostoma. Shell ovate or globose, thick and nearly smooth, 

 with a moderately elevated spire : aperture ovato-lunate, the lips 

 meeting above at a sharp angle ; outer lip furnished internally along 

 its whole extent with a thickened edge, which is repeated at regular 

 intervals and accompanied by a temporary lengthening upwards of 

 the aperture ; inner lip callous and spread over the body-whorl so 

 as almost to conceal the columella. 



Tylostoma Torrubi^, nobis. 

 Torrubia, I.e. pi, 10. fig. 4. 



Shell ovate, slightly flattened, with a produced spire formed of 

 about 8 ? volutions ; whorls evenly convex. Internal callosity of the 

 outer lip broad and flattened, repeated every half volution, and ac- 

 companied with a slight elongation of the mouth upwards. 



Length 4 inches ; breadth 2 inches in one direction, 2\ inches in 

 the other. 



Spiral angle about 65°. 



From the thickening of the lip occurring at about every half volu- 

 tion, the shell has somewhat of the flattened form of Ranella : in 

 other respects this is less irregular, and shows the peculiarities of 

 the geaus less strongly than any of the other species. I have only 

 seen internal casts. 



Very abundant in the limestones of the subcretaceous series, in 

 which it has been found at the following localities : — Condeixa ; 

 San Fagundo, about 1^ league west of Coimbra ; Sarjento-mdr, 

 about l^ league north of Coimbra ; Figueira ; Mamarosa, on the 

 road from Aveiro to Coimbra ; and in the cliff's north of Cintra at 

 the Praia de Ma9ams. 



Plate IX. fig. 1 . Internal cast. 



Fig. 2. The same on the side of the mouth. 



Tylostoma punctatum, nobis. 



Shell broadly-ovate, with a pyramidal spire formed of about 6 vo- 

 lutions : whorls convex, tabulated above, giving a step-like outline to 



