Manwick.—The Struthiolariidae. 163 
The following is an attempt to discover the phylogeny of the family by 
following the ontogeny of some characteristic species. 
Well-preserved examples of the Recent and Pliocene &. papulosa and 
smooth, bulbous, capuliform structure, with its long axis at right angles 
to that of the shell (a particularly large and projecting example is figured 
in text-fig. 3, a—c). That this is the true protoconch is shown by the 
Fie, 3.—Protoconch of Struthiolaria vermis. х 6. 
appearance of the same feature on specimens of S. conveza n. sp. from the 
Pliocene of the Ngaruroro River. In withdrawing from the embryonic 
e 
easily broken off, a planorbid apex is the result. It is probable that 
this type of protoconch prevails throughout the genus, for the smooth 
planorbid tip, generally seen in all well-preserved shells, is followed by a 
convex, striated conch-whorl similar to that SR the deviated proto- 
conch of the examples cited above. 
1. Genus MoNaLamnia n. g. 
pepares Struthiolaria tuberculata concinna Suter. 
a.) S. lirata Tate. The first volution of the conch in all species of 
New Zealand Struthiolariidae is a convex whorl with about six ua A 
spiral threads separated by interspaces of slightly 
greater width, and, as far as seen, all starting at 
practically the same time. This indicates that = 
primitive type from which the various species 
descended was a round-whorled shell with in 
regular-spaced spirals, a condition well represented 
by Struthiolaria lirata Tate from the Gippsland 
Lakes (Tate, 1889, p. 169, pl. x, fig. 11). (See 
text-fig. 4.) 
he figure shows that this =. эли a straight ы ie 
columella, and little callus on the in ip though — "Struthiolaria" lirata 
the outer lip is thickened. That a онда advance * 
has been а on the primitive type is indicated лы ДЕУ Мө) 
by Tate's description of secondary spirals in the interspaces of the 
body-whorl. The growth-lines are stated to be “sigmoidal,” which 
6* 
