in the Carboniferous Limestone of Clifton. 489 



Serjmla omphalodes (Goldf.), PJ. XVIII. fig. 1. 



Volutions from one and a half to two^ the last rapidly enlarging; 

 aperture acutely oval ; shortest diameter ^j inch, longest dia- 

 meter y- inch. 



Pleurotomaria ■pygmaa (n. sp.), figs. 2 & 2 ff. 



Trochiform ; whorls three to four, slightly keeled at outer edge 

 of the last volution, which last has a slight depression on its 

 upper surface ; height and breadth nearly equal, viz. about 

 ^-Q inch ; the last whorl also more extended than the others. 

 Some specimens exhibit traces of a raised ornamented band. 

 Aperture semilunar. 



These casts remind the observer strongly of those so often 

 found in the Inferior Oolite; but as here they exist as casts 

 only, they cannot be identified with any of the larger and more 

 perfect Carboniferous forms figured by Portlock or Phillips, 

 and must, at any rate for the present, be regarded as a distinct 

 species, both from the constancy of their size and some marks 

 distinctive from those species more commonly known. 



Tm-ritella siduralis (Phill.), fig. 3. 



Shell elongato-conical ; whorls broad, prominent at upper and 

 lower edges ; base slightly swollen ; about four volutions in 

 — inch ; aperture somewhat semicircular. 



These casts so nearly resemble the full-sized specimens in the 

 Bristol Museum, which occur not far from the same spot, that 

 the author has no hesitation in regarding them as identical, the 

 only difference being that of age. 



Euomphalus iriangulatus (n. sp.), fig. 4. 



Whorls three to four, slightly keeled at the upper part of each 

 volution, which is there shghtly swollen, giving the aperture 

 a subtriangular shape. 



This peculiarity is so different from any in the same section 

 as to induce the author to give it the above specific term. 



Cy there oralis (n. sp.), figs. 5, 5 ff, 5 b. 



Valves oval, very convex ; longitudinal ridge very distinct ; ends 

 of valves thickened and extending inwards, forming a kind of 

 flange. In a few instances traces of denticulation occur at 

 each end of base. Length -^^ inch ; height /- inch. 



This is undoubtedly a Cythere, both from its form and the 

 strictly marine origin of the bed. 



