340 



ARTHROPOD A. 



tected in the Silurian formation of Bohemia, Britain, and 

 North America. The distinguished Bohemian palaeontolo- 

 gist just mentioned regards Turrilcpas not as being the scaly 



Fig. 200. A, Turrilepas Wrightii Upper Silurian (after Woodward) : a, A plate of the 

 same magnified. B, Loricula pulchella Chalk (after Darwin). 



peduncle of a form like Loricula, but as being truly the 

 capitulum of a Lepadoid, in which the peduncle is wanting 

 or rudimentary. Another Silurian genus of Lepadoids has 

 been described by Barrande under the name of Anatifopsis. 

 Only detached valves are known, which have a general like- 

 ness to those of Lepas, each valve being somewhat quadri- 

 lateral, and having the lower part of its base marked out 

 into one or two horizontal segments, which are more or less 

 separated from the body of the valve. ISTo undoubted pe- 

 dunculated Oirripedes have as yet been detected in the 

 Devonian, Carboniferous, or Permian rocks ; and, with the 

 exception of the ancient types just mentioned, the oldest 

 known representatives of the Lepadoids belong to the genus 

 Pollicipes, species of which have been discovered in the 

 Ehsetic beds (Upper Trias), and in the Stonesfield Slate 

 (Lower Oolites). In the Cretaceous period, the Lcpadidce 

 reached their maximum of development, about 80 per cent 

 of the known fossil forms having been recognised in strata 

 of this age. The Tertiary forms are few in number, and 

 belong to the genera Scalpellum, Pollicipes, and Pcecilasma, 

 the last being only a sub-genus of the living Anatifa. 



