1849.] SHARPE ON THE SECONDARY ROCKS OF PORTUGAL. 193 



oblique : colour tawny, with thin dark lines radiating from the apex 

 to the margin, some of which bifurcate ; these are crossed by well- 

 marked lines of growth. Aperture semi-lunar ; body-lip expanded 

 into a gibbose callosity ; outer lip sharp and extended to the two 

 ears. 



Length f of an inch ; breadth ^ an inch. 



Found in limestone of the subcretaceous series, two miles south- 

 west of Alenquer. 



This curious shell belongs to the division of the Nerites, of which 

 Neritina aimculata, Lam., is the type ; but it is more nearly equi- 

 lateral than any recent species. There can be little doubt that it 

 must have inhabited fresh water, but all the shells found near it belong 

 to marine genera. The colours are most remarkably preserved. 

 Only one specimen has been seen, of which the spire is not quite 

 perfect. 



Pyramidella? sagittata, n. s. Pl. XX. fig. 8. 



Shell conical, short, smooth. Spire of four or five whorls, which 

 enlarge rapidly, the last whorl forming about half the length of the 

 shell. Mouth narrowed by two strong thick plaits on the columella, 

 which are continued through the whole spire ; the upper plait pro- 

 jects diagonally, the lower horizontally, until they nearly meet 

 and divide the interior of the whorl into three lobes, giving the 

 section a resemblance to the head of a broad arrow. Columella 

 umbilicated. 



Length 2\ inches ; breadth 1 inch. 



Spiral angle 4.5°, regular, Sutural angle 55°. Basal angle 120°. 



Found in limestone of the subcretaceous series, in the cliffs of the 

 Praia de Adrarga, north of the Cintra hills. 



Unfortunately all the specimens of this very curious shell are im- 

 perfect, and the specific characters rest principally on the enormous 

 size of the fold of the columella, and the form of the interior of the 

 whorl. In general it is hardly advisable to name such a fragment, 

 but in this shell the internal characters are so very remarkable as to 

 justify gi^^ng it a name, although we have seen little more than a 

 section of the shell., I have placed it in Pyramidella with some 

 hesitation, as it has little resemblance in general appearance to the 

 other species of that genus : it differs from Nei^incea in the simple edge 

 of the outer lip and the rapidity of increase of the whorls. 



Rostellaria Cost^, n. s. Pl. XX. fig. 1. 



Shell elongato-conical ; spire regular, of eight or more volutions ; 

 whorls gibbose, smooth in the middle, but ornamented round their 

 upper edge with short reflexed folds, and round their base with longer, 

 faint, oblique folds sloping forwards ; several concentric grooves round 

 the base of the body -whorl. 



Length 3^ inches ; diameter 11 inch. 



Spiral angle 35°. Sutural angle about 90°. 



Found in limestone of the subcretaceous series at San Pedro de 

 Muriel, near Meirinha Grande, by Dr. F. A. Pereira Costa, to whom 

 I am indebted for the specimen, and after whom it is named. 



