Marwick.—The Struthiolariidae. j 165 
while on the base are two strong spiral cords. Other and more developed 
species of the group show the axials abbreviated to rounded tubercles with 
many pisni spirals below. The columella is in most cases only slightly 
bent ; n 8. nordenskjoldi Wilckens the curvature is marked, and the 
callus is pit developed, cue. that a gerontic stage has been reached. 
n all cases the outer lip has the same contour as that of Monalaria—i.e., 
быш is one prominent еве 
ће elopment of strong spirals on the base shows that this group 
branched of from Monalaria sensu lato before the development of such as 
M. concinna, but it may have come through M. minor. The age of these 
two species cannot defintely be placed on the European time-scale, but the 
probabilities are that the latter is about Palaeocene and the former Oligocene. 
The curvature of the columella and the spread of the callus in mature 
Ета. 6.—a, b. Struthiolareila ornata (Sowerby). (After Ortmann.) 
с. S. ameghinoi von Ihering. (After Ortmann.) 
d, е. S. nordenskjoldi Wilckens. (After Wilckens.) 
"vus T Steinmann and Wilckens, 1908, figures of S. ameghinoi, 
Es and S. nordenskjoldi Wilckens, 1911, pl. 1, figs. 26, a, b— 
„ай to the strong basal spirals, justify the generic separation of 
Struthiolarella from Monalaria, while the XM of the outer lip and the 
ornamentation separate it from Struthio 
Wilckens later (1922, p. 17) tentatively ae 
gested coe 8. е? was wrongly 
classed eghinoi, and was more 
closely кд to аа расии. The 
writer does not agree with this, and considers 
S. nordenskjoldi to be a gerontic development 
of Struthiolarella. 
Under Struthiolarella, Steinmann and 
Wilckens included Tylospira coronata (Tate) 
from the Lower Tertiary of Victoria, and the 
living Struthiolaria mirabilis Smith from Ker- 
guelen Land, not granting generic recognition 
to Tylospira as based on scutulatum. 
Previously Tate (1889, p. 170) had included 
the Kerguelen shell with T7. coronata an 
T. scutulata in his ae of the genus 
Pelicaria (i.e., Tylospir 
Though t e apertutal callus is lacking, S. mirabilis certainly is similar 
to S. а але, and is perhaps rightly associated with Struthiolarella ; but 
Struthiolarella mirabilis (Smith). 
(After Tryon.) 
