112 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 1, 



I refer my shell to N. nohilis with some hesitation, because it 

 never reaches the size of the specimen figured by Goldfuss from Salz- 

 burg, and it is only in its younger state that it has the pupoidal form 

 of his species. Before reaching half the diameter of his specimen the 

 Portuguese shells have usually become nearly or quite cylindrical ; 

 still I can find no distinctive characters upon which to found a new 

 species. Most of the specimens found at Lisbon are internal casts, 

 and neither in that state nor in the section can they be distinguished 

 from N. nodosa of Voltz, with which I confounded them till specimens 

 were found covered with the shell : the latter species has not been 

 found at Lisbon. In the casts each whorl appears deeply divided 

 into two rings ; in the young shell, fig. 1 b, the lower ring is narrower 

 and rounder than the upper ; but in older shells, fig. 1 c, the two rings 

 are nearly equal, and in this state the casts resemble those of N. Bor- 

 soni, which may perhaps be the same species. 



Plate XII. fig. 1 a. Exterior of a young shell. 



Pig. 1 b. Cast of a young shell. 



Fig. 1 c. Cast of an old shell. 



Pig. 1 d. Section of a shell nearly full-grown. 



NeriNtEA Titan, n. s. 



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

 "Whorls very numerous, deeply concave in the middle ; equal in height 

 to one-third of the diameter of the shell ; hardly increasing in size in 

 the old shell. Suture in the middle of a broad high ridge. Mouth 

 nearly square. Columella solid, occupying one-fifth of the diameter 

 of the shell. Three folds in the interior, of which one on the middle 

 of the outer lip has a broad base and sharp edge projecting but little ; 

 one on the columella slightly below the former projects thin and sharp 

 beyond the middle of the whorl ; one on the top of the whorl, sharp 

 and smaller than the last, and curving outwards. 



Sutural angle about 85° when young, 95° to 100° when old. Basal 

 angle 105°. Spiral angle in young shells about 20°; when old the 

 shell is so nearly cylindrical that in a fragment 5 inches long the dia- 

 meter only increases one-eighth of an inch. Greatest diameter 2\ 

 inches. 



Very abundant in the limestone beds of the subcretaceous series in 

 the cliffs north of Cintra, especially at the Praia de Ma9ams, where a 

 bed several feet thick is entirely formed of the debris of these shells. 



This species resembles N. gig ant ea, which it fully equals in size, 

 but it is readily distinguished by a flatter base to the whorl and 

 squarer mouth, and by the two inner plaits projecting farther inwards ; 

 it is also closely related to N. Goodhallii. 



Plate XII. fig. 3 a. Exterior. 



Fig. 3 b. Section. 



Subgenus 3. Trochalia. 



NeriNyEA annulata, n. s. 



Shell conical, smooth, with projecting broad rings : spiral angle 25°, 

 regular. Whorls numerous, deeply concave, one-fourth as long as they 



