170 PATAGONIAN EXPEDITIONS I PALAEONTOLOGY. 



Gen. GIBBULA Riss. 

 102. GIBBULA L/EVIS (Sowerby). 



PI. XXXI, Fig. 8. 



1846 TrocJms Icevis Sowerby, in: Darwin, Geol. Observ. S. Amer., p. 256, 



pi. 3, f. 46, 47 (adult). 



1846 T. collaris Sowerby, ibid., p. 256, pi. 3, f. 44, 45 (junior). 

 1887 T. Icevis Philippi, Tert. & Quart. Verst. Chiles, p. 101, pi. 12, f. 5. 

 1897 Gibbula coll. v. Ihering, in: Rev. Mus. Paul., v. 2, p. 273. 

 1899 c - v - Ihering, in: N. Jahrb. Miner., etc., v. 2, p. 24. 



Shell conical, broader than high, umbilicated. Surface smooth, whorls 

 almost flat, only the last one slightly convex. Periphery sharply angu- 

 lated. Upper whorls, close to the suture, with a series of small tubercles. 

 Base very slightly convex, with a deep umbilicus of medium size, and a 

 number of fine revolving striae, which are distinct near the umbilicus, but 

 disappear toward the periphery. 



Height (not complete), 28 mm; diameter, 51 mm; according to Phil- 

 ippi : height, 38 mm ; diameter, 50 mm. 



Remarks: Philippi was the first to recognize that T. collaris of Sowerby 

 is only the young stage of T. lcevis, and he retains the specific name of 

 the old stage. V. Ihering again uses the specific name of collaris, preced- 

 ing that of Iczvis in Sowerby's text, but according to the rules of nomen- 

 clature, we are to follow Philippi, who was the first to make a selection 

 between the two names available. 



In some specimens the small tubercles near the suture disappear later 

 than in others. The lower surface of the shell has spiral striae, which in 

 very young ones are very faint near the periphery, and disappear in old 

 shells altogether, with the exception of 5 to 7 close to the umbilicus (see : 

 Sowerby's figure 47). 



Record of specimens: Mouth of Santa Cruz River, i2sp.; Las Salinas, 

 i sp.; San Julian, Oven Point, 2 casts; Lake Pueyrredon, base of Ter- 

 tiary, 2 casts ; Lake Pueyrredon, 600' above base, i cast. 



Distribution: Patagonian beds of Santa Cruz (Sow., v. Ih.); Navidad 

 (Sow., Phil.), Lebu (Phil.). 



Affinities: A very closely allied species is T. veneficus Philippi (1887, 

 p. 101, pi. 12, f. 8), from Navidad, but the latter has a blunt, but distinct 

 angulation near the suture, on which the tubercles are placed. 



