208 PERMIAN FOSSILS. 



(?) RissoA MiNtJTissiMA, Brown. Op. cit., vol. i, p. 64, pi. vi, figs. 12, 14. 



— — AND OBTUSA, 5ro2cw. Brown, Fossil Conchology, p. 79, pi. x.wvii*, 



figs. 28-30, 34-36. 



— — — „ Morris, Catalogue, p. 161, 1843. 



— — — „ De Verneuil, Bull. Soc. Geol. de France, 



2"" serie, vol. i, p. 36, 1844. 



— — — „ Geol. Russ., vol. i, p. 225, 1845. 



— — — „ Tennant, Strat. List, p. 89, 1847. 

 (?) Trochus pusillus, Geinitz. Versteinerungen, p. 7, pi. iii, figs. 15, 16, 1848. 



Diagnosis. — " Shell ovate, smooth, ventricose ; spire nearly equal to the body in 

 length, consisting of three depressed, subturreted volutions, divided by a deep suture ; 

 aperture nearly orbicular ; pillar lip not reflected, but provided with a slight umbiUcus 

 at the base of the columella. Length upwards of a quarter of an inch ; diameter not 

 quite so much." (Brown.^) 



There is in one of the original specimens of this species belonging to Mr. Binney an 

 important character, which Captain Brown seems to have overlooked, namely, a broad 

 sinus in the upper half of the outer lip, as indicated by the incremental lines, which 

 are represented in fig. 18, PL XVI. This character throws considerable doubt on the 

 present generic position of the species ; and somewhat favours the view that it belongs 

 to the genus Macrockeilus. 



Bissoa obtusa is recorded as occurring in the Magnesian Marls at Collyhurst 

 (Captain Brown) : it also occurs in the same formation at Bedford, ten miles west of 

 Manchester (Binney). 



RissoA Leighi, Brown. Plate XVI, fig. 15. 



RissoA Leighi, Brown. Trans. Manch. Geol. Soc, vol. i, p. 64, pi. vi, figs, 9-11, 1839. 



— — „ Fossil Conchology, p. 79, pi. xxxvii, figs. 25-^27, 1841. (?) 



— — „ Morris, Catalogue, p. 161, 1843. 



— — ,, De Verneuil, Bull. Soc. Geol. de France, 2""' serie, vol. i, p. 36, 



1844. 

 _ _ „ Geol. Russ., vol. i, p. 225, 1845. 



— — „ Tennant, Strat. List, p. 89, 1847. 



Diagnosis. — " Shell smooth, oblong-ovate ; spire long, consisting of four deeply 

 divided, inflated volutions, terminating in a somewhat obtuse apex ; aperture ovate, 

 slightly contracted above, and rounded at the base ; columella subumbilicated. Length 

 one eighth of an inch ; breadth one fourteenth of an inch." (Brown.2) 



" Found in the Magnesian Marl at Collyhurst, and is in Mr. Binney 's cabinet."* 



^ Transactions of the Manchester Geological Society, vol. i, p. 118. 



2 Ibid., p. 64. 



3 Vide Brown's Fossil Conchology, p. 79. 



