( ^>1 ) 



Darwin pointed out the resemblance of tliese two genera already 

 in 1851^). That resemblance is greatest in those siiecies oï Scalpellum 

 in which the cai'ina is not bowed or angularly bent, but straight or 

 nearly straight. Darwin gave as an interesting case of such a species 

 a description of Sc. villosiiui (fig. 2 of the accompanying plate). He 

 was so struck by its general likeness to Follicipes, that he wrote 

 (I.e. p. 278): "Sc. villosiim most closely resembles or rather is identical 

 with Pollicipes. Had it not been for the fewness of the valves 

 forming the capitulum, and from the presence of complemental males, 

 I should have placed this species alongside of Pollicipes spinosus and 

 sertus." And under Pollicipes (I.e. p. 294): "We have seen under 

 Scal])ellum villosum that the addition of a few small valves to the 

 lower whorl, would convert it into a Pollicipes" etc. Compare fig. 3 

 of the accompanying plate. 



The genus Scalpellum is represented under the deepsea animals by 

 numerous species. Those of Pollicipes are shallow water forms only. 

 The English "Challenger" Expedition collected during a four years' 

 cruise over all the oceans of the world, specimens of 42 different 

 species of Scalpellum, 41 of which were new to science. Only two 

 of these were found in depths of less than 200 in.: all the others 

 were true deep-sea species. H.M. "Siboga" collected in the Malay 

 Archipelago, during a cruise of one year's duration, specimens of 

 38 different species of Scalpellum. Of these, 32 must be considered 

 as new to science; 34 of these species are deepsea animals, 4 shallow- 

 water forms. 



The genus Pollicipes was not represented under the Cirripedia of the 

 Challenger and by one species only under those of the Siboga: 

 Pollicipes mitella a common littoral form of tropical seas. Whereas 

 the number of known living species of Scalpellum was 6 in 1851 

 and is at least 125 at the present time (so far as 1 know ")), of 

 the genus Pollicipes which figures in Darwin's book with 6 species 

 also, only a seventh species has been described since the appearance 

 of the said monograph. When Darwin wrote that book the mysteries 

 of the oceanic abysses were not unveiled to him of course, but his 



1) Darwin, C, A Monograph on the Subclass Cirripedia. I. The Lepadidae or 

 pedunculated Girripedes. 1851. 



2) Including the species collected by the Siboga. A. Gruvel, who described the 

 species collected by the French expeditions with the Travailleur and the Talisman, 

 and G. Aurivillius, who studied the Cirripedia of Swedish collections and published 

 provisional descriptions of the Cirripedia collected by the Prince of Monaco during 

 his numerous cruises have, with the present author contributed most to our know- 

 ledge of the species of tliis genus. 



