221 
this, we may conclude that the reduction of the males at all events 
in some genera has set in at a late period, after the skeleton hav¬ 
ing reached a high specialisation in both sexes. — The high de- 
velopment of the male, and the variating features of the lower 
whorl of plates in the capitulum indicate that Calantica occupies 
a low stage in the phylogenetic series. In the nearly related genus 
Smilium the male attains an almost equally high organisation as 
in Calantica, or is a little more reduced; on the other hånd, one 
of the latera — viz. latus superius — has in the hermaphrodite 
(or female) emancipated itself from the lower whorl of latera and 
reaches a higher development. In the reduction of its dwarf males 
the Euscalpellum- group (by Pilsbry 1908 separated out as a ge¬ 
nus of its own) leads on to Scalpellum where the reduction of the 
male is continued, till in some species it is entirely done away with; 
moreover the subrostrum and subcarina have disappeared in the 
skeleton of the great form. The last step in this line of develop¬ 
ment leads to the new genus Scalpellopsis described below; here 
the anterior latera are also reduced so that only the posterior latera 
persist. 
From Calantica the development has taken another course to 
Protomitella. The male is kept here, although it does not seem 
to occur abundantly; its organisation is the same as in most spec¬ 
ies of Calantica. In the hermaphrodite the upper row of pedun- 
cular scales attain a peculiar, high development and join the capi¬ 
tulum skeleton as a lower row of accessory small latera; the 
constant appearance of a subcarina, and the somewhat variating 
development of the principal latera known in Calantica give evid- 
ences of near relationship. From Protomitella there is but a short 
step to Mitella, where the male has entirely disappeared, and where 
an upper row of latera is generally, although not invariably, more 
developed than the accessory, lower latera, here designated as 
emancipated upper scales of the peduncle. Nearly related is also 
Lithotrya, in which genus the male is likewise wanting; here it is 
obvious that the upper row of stalk scales, although highly devel¬ 
oped, do not in reality belong to the capitulum skeleton. 
Finally also another genus naturally belongs to this group, viz. 
Ibla, in which calcification has been abandoned, and where, ac- 
cordingly, only the primordial plates persist, with exception of the 
