1849.] SHARPE ON THE GENUS TYT.OSTOMA. 379 



the spire. Surface ornamented with numerous transverse rows of mi- 

 nute punctations set in shallow furrows, wiiich are crossed by fine lines 

 of growth : the rows of punctations are rather distant in the upper part 

 of the whorl, but are crowded closely together near its base. Mouth 

 ovate, the upper angle somewhat rounded : outer lip wath a very broad, 

 thick, internal callosity, which is repeated once in each volution. 



Length ly inch ; breadth 1^ inch. 



Spiral angle about 70°. Sutural angle about 60°. 



Abundant in limestone of the subcretaceous series at the village of 

 Sarjento-mdr, l^ league north of Coimbra on the road to Oporto. 



To the naked eye this shell appears nearly smooth, and it requires 

 a lens to show clearly the minute punctations which cover it : these 

 closely resemble the markings of Natica cassisia7ia, D'Orb. Terr. 

 Cret. pi. 175. fig. 3, but the shells may be readily distinguished by 

 the more tabulated outline of the Portuguese species. 



Fig. 3. A specimen with the shell partly broken off. 



Fig. 4. Another specimen on the side of the mouth. 



Fig. 4«. Portion of the surface of the upper part of the whorl, 

 magnified. 



Fig. Ab. Portion of the surface of the lower part of the whorl, 

 magnified. 



Tylostoma globosum, nobis. 



Shell globose, with a very short spire formed of about 6 volutions : 

 whorls rounded, nearly smooth, marked only with very faint lines of 

 growth. Mouth narrow : outer lip with a thick subdenticulated in- 

 ternal longitudinal callosity, which is repeated at intervals equal to 

 fths of the volution, and accompanied by a considerable rise in the 

 upper margin of the whorl. 



Length 2^ inches ; breadth 2\ inches in one direction. If inch in 

 the other. 



Spiral angle rounded, between 100° and 110°. 



Sutural angle varying in different parts of the whorl from 120° to 

 140°. 



Abundant in limestone beds of the subcretaceous series at the 

 following localities : — Figueira ; one league west of Montemor velho ; 

 San Fagundo, 1^ league west of Coimbra; Sarjento-mor, 1^ league 

 north of Coimbra. Rare in the upper beds of the hippurite lime- 

 stone on the west side of Lisbon. 



Perhaps Globiconcha rotundata, D'Orb. Terrains Cretaces, pi. 169. 

 fig. 17, may be the young of this shell before it has begun to form 

 the callosities inside the lip. 



Fig. 5. A cast from the subcretaceous beds. 



Fig. 6. Another specimen from the same beds, with a portion of 

 the shell preserved. 



Tylostoma ovatum, nobis. 



Shell broadly-ovate, with a moderately produced spire formed of 

 about 6 volutions : whorls convex : mouth subovate : outer lip with 

 a very thick, subdenticulated, internal callosity, which is repeated 

 at intervals equal to about fths of the volution, and is accompanied 

 by a very considerable rise in the upper margin of the whorl. 



VOL. V. — PART I. 2d 



