168 Transactions. 
This resemblance is so close that Suter granted only varietal ran nk to 
M. concinna, though why he considered it a variety of S. tuberculata is 
hard to keiten; 
(b.) S. callosa Group. 
At different localities in the rocks of Upper Miocene and perhaps Lower 
Pliocene age there are several species of Struthiolaria which have a some- 
what strange appearance. These shells agree with Struthiolaria s. str. in 
all essential features, but there is a huge development of the rather 
flat pad on the inner lip. This callus-pad surmounts the shoulder, even 
burying the long tubercles, generally reaching the posterior suture, but 
rarely adhering to the whorl above. On the outer part of the base the pad 
protrudes and has a vertical face exteriorly ; ; but between this knob and 
the anterior beak is a deep smooth channel with only a thin layer of enamel. 
The pad is rounded off somewhat abruptly at its upper junction with the 
outer lip, forming another channel on the shoulder. The outer lip is 
sliokenod and DAR but no more so than in the typical Struthiolaria. 
Tn the sutures on the later spire-whorls a layer of enamel is generally 
ym c sometimes ыйа to the row of tubercles on the shoulder (see 
At least four species are вака but they may not form a natural 
group distinct from the S. papulosa group ; for, while S. callosa, apart from 
the callus, agrees closely with S. spinosa, S. armata appears to be just as 
closely related to S. spinifera. This might mean that the great callus is 
produced by a parallel development of different species. 
The following table distr a suggested ancestry of the species belonging 
to the two foregoing groups : 
S. obesa 
S. rais S. dibus S. armata S. frazeri 
| J S. tuberculata S. cingulata 8. papulosa 
S. tro S. RUE S. calcar S. RO S. Ne 
| а с 
| Марте PE 
S. subspinosa 
M. concinna 
M. minor. 
(c.) S. vermis Group. 
The shells belonging to this group form a well-defined series attaining 
considerable development in the Wanganuian (Pliocene) of New Zealand. 
y one specimen has been seen from a lower horizon, the Tawhiti series, 
East Cape, which may be of Upper Miocene age. This shell is much 
distorted, but there is no doubt that it belongs to the group, being closely 
allied £o S. acuminata n. sp. 
A study of the neanic shell of S. vermis shows that the first conch- 
volution is regularly convex, with the usual five or six spirals. On the 
g n later spire-whorls in some species (ex. S. canaliculata) a third 
cingulus appears posteriorly. 
