ORTMANN : TERTIARY INVERTEBRATES. 22y 



of the mouth to the whole shell, and in the longitudinal sculpture. The 

 longitudinal ribs end abruptly before reaching the suture, forming a dis- 

 tinct shoulder, and sometimes this shoulder is marked by a distinct tuber- 

 culiform development of the ribs. In all other characters this species is 

 extremely variable. The external form is more or less slender : there are 

 some individuals, which are as slender as the following species (V. grac- 

 ilior}; the upper whorls are sometimes about half as high as broad, some- 

 times almost as high as broad ; the spiral cords are more or less devel- 

 oped ; the number of longitudinal ribs is very variable, between 8 and 16, 

 and, further, the number of columellar plaits varies from 2 to 4. 



Even the character of the longitudinal ribs is not quite constant ; some- 

 times their upper termination is less sudden, and, indeed, there are indi- 

 viduals which approach the following species also in this respect. 



v. Ihering says (under V. alto], that the transition from the mouth into 

 the canal is well marked by an obtuse angulation : I cannot see anything 

 like that in any of our specimens : the outer lip of the mouth passes in a 

 regular curve into the canal. 



I possess two young individuals, which show the nucleus of the shell. 

 It corresponds closely to what Ball (1890, p. 68) calls the Caricella-nncletts 

 (see plate XXXV, Fig. 4 rf> '), with a distinct small point or apical spur. 

 This species is, accordingly, not to be classed with the Volntoid-series, as 

 Dall(p. 69) does, but with the Scaphelloid-series (ibid., p. 70). I may men- 

 tion here that we have the same nucleus in V. dorbignyana, and it is quite 

 probable that the other Patagonian species also belong to the same type, 

 which fact would bring them into closer relation with the living Volutce 

 (Gen. Scaphelld] of Patagonia (V. ancilla, magellanica, etc.). 



Record of specimens : Mouth of Santa Cruz, 1 3 sp. 



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

 Chili: Navidad (Sow., Phil.), Matanzas (Phil.). 



157. VOLUTA GRACILIOR v. Ihering. 

 PI. XXXV, Fig. s-. 



1887 V. gracilis Philippi, Tert. & Quart. Verst. Chiles, p. 70, pi. 7, f. 13 



(non V. gracilis Lea, 1833). 



1896 V. gracilior v. Ihering, in: Nachr. deutsch. malakozool. Ges., p. 96. 

 1896 V. queniadensis v. Ihering, ibid., p. 97. 



