ORTMANN : TERTIARY INVERTEBRATES. 
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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. subcequalis. 
This species grows much larger. Philippi gives : Height, 33 mm, 
diameter, 11 mm, and v. Ihering: Height, 45 to 50 mm. 
Record of specimens : Mouth of Santa Cruz River, 1 sp. 
Distribution: 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. 
166. Pleurotoma unifascialis v. Ihering. 
PI. XXXVI, Fig. 7 a '\ 
1897 P- discors var. unifascialis v. Ihering, in: Rev. Mus. Paul., v. 2, 
p. 312.. 
1900 P. unifascialis 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 
