(92 ) 



knowledge of the existing shallow-water forms of Cirripedia was 

 fairly complete. 



Returning to the interesting species Sc. villosum, the near affinity 

 of which to Polliclpes was pointed out by Darwin, I may mention 

 first, that in my Rci)ort on the Cirripedja of tlie Challenger I was 

 able to describe a species {Sc. trispinosum) belonging to the same 

 division of the geuus. It was collected in the Philippine Archipelago 

 at a depth of 150 (perhaps 180 meters). Next, that the Siboga was 

 successful in finding two more of them and that these will bear 

 the names of Sc. poUicipedoide.'^ and Sc. ones. Though the capitulum 

 of both species resembles the common form of ScaJpeUum (compare 

 tig. 1) more than that of either *St'. trispinosum or Sc. villosum, the 

 shape of the carina shows their affinity to the last named species 

 at once. 



These species were also taken in rather shallow water: in depths 

 varying between 57 and 94 meters. The depth at which Sc. villosum 

 lives is not so well known, but it cannot be important. Darwin 

 says that the specimens were found attached to shells and rocks: 

 they were taken no doubt during shore-exploration. 



So we can say that those species of Scalpellwn which resemble 

 Pollicipes most closely, like all known species of that genus itself, 

 are inhabitants of shallow water. Pollicipes as is well known, 

 embraces the oldest known Cirripeds and the genus Scalpellum is the 

 second in age. The structure of ^Sc. r/Z/cvw;//! makes it highly probable 

 that the genus Scalpellum descended from Pollicipes. This supposition 

 finds very striking confirmation in a peculiarity of one of the 

 specimens of Sc. pollicipedoides, which peculiarity I shall briefly 

 describe here. 



The said species is represented in the Siboga-collection by six 

 specimens. It was found at Station 274 near the Jedan Islands, 

 south of New Guinea, at a depth of 57 meter. Its capitulum has 

 15 valves: two scuta of triangular, two terga of rhomboid shape; 

 a nearly straight carina, two rather small upper latera and eight 

 valves of the lower whorl. Of these the rostrum and the sub- 

 carina have the umbo pointing transversely outwards; of the three 

 pair of latera which, with rostrum and subcarina form the lower 

 whorl, those of the middle pair are by far the smallest. The shape 

 of all these valves is triangular with the umbo at the apex. 

 Whereas the scutum and the tergum stand rather close together, 

 the other valves are far apart, being separated from one another 

 by chitinous membrane. 



Though, as I pointed out above, the general shape of the capitulum 



