1849.] SHARPE ON THE GENUS NERIN^A. Ill 



N. cylindrica, Voltz and Bronn, Jahrb. 1836, t. 6. f. 16 ; in sub- 

 cretaceous limestone at Sarjento-mor, six miles north of Coimbra, 

 and in the cliffs at the Praia de Adrarga near Cintra. 



N. gigantea, D'Hombres-Firmas, Mem.; D'Orb. Terr. Cret. 2. t.]58. 

 f. 1, 2 ; in subcretaceous limestone at Alenquer. 



N. Titan, nobis, t. 12. f. 3 ; in subcretaceous limestone in the cliffs 

 at the Praia de Ma9ams near Cintra. 



Subgenus 3. Trochalia. 



N. annulata, nobis, 1. 13. f. 1 ; in subcretaceous limestone at Alenquer. 



N. grandis, Voltz and Bronn, Jahrb. 1836, t. 6. f. 1; in subcreta- 

 ceous limestone at Alenquer. 



N, turbinata, nobis, t. 12. f. 2; in subcretaceous limestone between 

 Sobral and Torres Vedras, and three miles south-west of Alenquer. 



Subgenus 4. Ptygmatis. 



N. Eschwegii, nobis, t. 13. f. 2 ; in the upper beds of the hippurite 

 limestone near Lisbon. 



N. Olisiponensis, nobis, t. 13. f. 3 ; in the upper beds of the hippu- 

 rite limestone near Lisbon, and in subcretaceous limestone at the 

 Praia de Ma9ams near Cintra. 



N. Bruntrutana, Thurmann ; Voltz and Bronn, Jahrb. 1836, t. 6. 

 f. 13 & 18 ; Goldf. t. 1/5. f . 5 ; in subcretaceous limestone at 

 Alenquer. 



N. Conimbrica, nobis, t. 13. f. 4 ; in subcretaceous limestone at Sar- 

 jento-mdr, six miles north of Coimbra. 



Description of the Species. 



Subgenus 1. NERiNiEA. 



NERiNiEA NOBiLis, Goldfuss, t. 177. f. 9. 



Shell turreted, smooth, conical when young, cylindrical when old. 

 Whorls numerous, very slightly convex, increasing slowly in size. 

 Suture running along a faint depression. Mouth elongated, with a 

 fold near the top of the outer lip and three folds on the columella. 

 Columella solid, nearly equal in thickness to one-fourth of the dia- 

 meter of the shell. Four simple folds in the interior, of which one on 

 the outer lip projecting half across the whorl in a slope parallel to 

 the base of the whorl ; two on the columella, of which the upper one 

 is the smaller, and nearly opposite to that on the outer lip ; and one 

 small fold on the top of the whorl sloping outwards. 



Spiral angle irregular, about 1 5° in the young, hardly perceptible 

 in the old shell. Sutural angle varying with the age from 100° to 

 110°. Basal angle* varying between 120° and 130°. Usual dia- 

 meter of old shells from |ths to 1 inch, rarely 1^ inch. 



Very abundant in the upper beds of the hippurite limestone near 

 Lisbon. 



* I have used the term basal angle for the angle formed by the meeting of the 

 side and base of the whorl. In this genus it furnishes a character by which many 

 species otherwise similar externally may be distinguished. 



