ORTMANN : TERTIARY INVERTEBRATES. 239 



In addition we should consider the fact that we do not possess in our 

 collection any form that might be taken for Fusus discors and so it is 

 quite probable that this Navidad species is not found at Santa Cruz, and 

 that the specimen referred to it by v. Ihering, although his description is 

 very meagre, really belongs to our species, the P. subczqualis. 



This species grows much larger. Philippi gives: Height, 33 mm, 

 diameter, u mm, and v. Ihering: Height, 45 to 50 mm. 



Record of specimens : Mouth of Santa Cruz River, i sp. 



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

 of Chili: Huafo Island (Sow.), Lebu, Matanzas, Navidad (Phil.). 



Affinities: Sowerby compares this species with an undescribed living 

 species from South America, but the identification of the latter is impos- 

 sible and the differences he mentions do not make the relation appear to 

 be a very close one. 



Among fossil forms there is one that much resembles our species : the 

 Miocene P. monilis Br. of Europe (see Hoernes, 1856, p. 353, pi. 38, 

 f. 14-16) : especially the presence of a tuberculiferous carina, and a few 

 stronger ribs below this on the last whorl are significant. 



1 66. PLEUROTOMA UNIFASCIALIS v. Ihering. 



PI. XXXVI, Fig. 7"'". 



1897 P- discors var. unifascialis v. Ihering, in: Rev. Mus. Paul., v. 2, 



p. 312. 

 1900 P. tmifascialis Ortmann, in: Am. Journ. Sci., v. 10, p. 381. 



Shell turrite, subfusiform. Whorls seven. Upper whorls covered with 

 a number of fine spiral threads and with a tuberculiferous carina below 

 the middle ; tubercles on this carina about 20 on the last whorl. Upper 

 part of whorls slightly concave. Last whorl large, longer than the spire, 

 sculptured as the upper whorls, but in addition there is, some distance 

 below the carina, a single, rib-like angulation. Canal moderately long, 

 sinus of outer lip situated on the tuberculiferous carina. 



Height, 17 mm; diameter, 7 mm. 



Remarks: The single, more strongly developed rib below the carina on 

 the last whorl, seems to be characteristic. V. Ihering says that this is the 

 first of the striae on the lower part of the shell, and this is apparently the 

 case in our specimen also. But a closer investigation reveals the fact that 



