The development of the calcareous skeleton in 
Mitella (Pollicipes ), and the origin of the Cirripeds. 
(Preliminary report) 
by 
Hjalmar Broch. 
Some years ago I published an account of the development 
of the calcareous plafes in Scalpellum l ). The investigations re- 
vealed the faet that in Scalpellum the „primordial valves“ (i. e. 
Carina, Terga, and Scuta) make their appearance before the other 
plates of the capitulum, and before the scales of the stalk; they 
are first observed in the pupa-stage as five small, chitinous plates 
of porous structure. This seems to indicate, as I have pointed out 
in the paper referred to, that the ancestors of Scalpellum must be 
sought among Cirripeds with a capitulum-skeleton consisting of only 
five plates, and I was inelined to share the opinion of Darwin 2 ) 
that Scalpellum descends from Oxynaspis-UkQ predecessors, and 
„blends through .S. villosum into Pollicipes“. This view is in 
strict opposition to the opinions maintained by Hoek 3 ) and Gru¬ 
vel 4 ) who consider Mitella (Pollicipes) to be the older genus, from 
which Scalpellum is derived; in their opinion Mitella among all 
the recent Cirripeds stands' next to the ancestral type. 
The only way to get a little more light into the question seems 
to be the detailed study of the development of the calcareous 
') Die Plattenentwickelung bei Scalpellum Stromii M. Sars. (Det kgl. norske 
Vid. Selsk. Sk. 1912). Trondhjem. 
2 ) A monograph on the Sub-Class Cirripedia. The Lepadidae or Peduncul- 
ated Cirripedes. (Roy. Soc.) London 1851. 
:1 The Cirripedia of the Siboga-Expedition. A Cirripedia peduneulata. Si- 
boga-Exped. Monogr. XXXI a. Leiden 1907. 
4 Monographie des Cirrhipédes ou Thécostracés. Paris 1905. 
6 * 
