( 93 ) 



is more like a. normal Scalpeliuin, in having one pair of latera more 

 than Sc. villosum or Sc. trispinosum, Sc. iwllicipedoides comef nearer 

 to Poliicipes even than those species. 



Looking over the six specimens of this new species, I Avas struck 

 by finding that one of the specimens, thongh in other regards similar 

 to the other five, differed from them by having in the lower whorl 

 of valves two latera in addition to the three whicli ail the specimens 

 possess. In fig. 4 the left side of a normal, in tig. 5 the same side 

 of the abnormal specimen is represented. (At the right side only one of 

 the additional valves is developed.) In fact, the few small valves 

 which according to Darwin were wanting in the lower whorl of 

 Sc. villosum to convert it into a Poll id pes occur in one of the 

 specimens of this new species. By calling it a case of reversion I 

 would indicate the high importance, which from an evolutionary 

 point of view I attach to this abnormality. We need not go so far 

 as to consider this species as representing exactly the "missing link" 

 between the genera FoUlcipes and ScaIj)eUum, but I think the case shows 

 clearly that a form with more numerous calcareous parts in its 

 capitulum (like PoUicipes) is the older, the form with fewer (like 

 Scalpelluni) the younger one; moreover, that the ScalpeUiim-species 

 with straight carinae, inhabitants of shallow water, must be considered 

 as the oldest, i. e. the species most resembling the primitive form 

 of Scalpellum. 



(It is perhaps not quite superfluous to remark here, that 80 of 

 the 125 species of Scalpellum have been studied and described by 

 myself and I never saw before such an augmentation of valves in 

 the lower whorl (or in the capitulum in general). Nor can I 

 remember to have met with descriptions of such cases in literature. 

 Darwin for the classification of the genera of Cirripedia made use 

 of the number, the shape and the mode of growth of (he valves. 

 That he was right in doing so is proved by the fact that later 

 authors never put in doubt the value of these characteristics). 



A full description of this and of the other new species of Scal- 

 pellum will be given in the forthcoming report on the Cirriiiedia of 

 the Siboga-Expedition. I wish however to point out here, tiiat Sr. 

 jwllicipedoides by the presence of a complemental male (Fig. 6) shows 

 itself to be a true Scalpellum and that it has rudimentary caudal 

 appendages which occur in PoUicipes also, but which curiously 

 enough according to Darwin are wanting in Scalpellum villosum. 



