CIRRIPEDIA. 



339 



sistent of the valves are the "scuta" (fig. 199, 6), which 



protect the front part of the body, and correspond with the 



valves bearing the same name in the operculum of the 



Balanoids. The next 



most important are the 



"terga" (fig. 199, a), 



which protect thedorso- 



lateral surface. A pair 



of scuta and a pair of 



terga are present, and 



these are the largest of 



all the valves. The 



"carina" and "rost- 



rum " are placed along 



the edges of the capi- 



tulum, the former being 



much the most import- /. . m-^^mmmw^m. d 



ant, and there may be 



a " sub - carina " and 



" sub - rostrum." The s 



remaining valves, with 



the Carina and rostrum, 



pnrrpcinnnrl wifh thp 

 Correspond Wltn tne 



DrODCr Shell Of the Ba- 



lanoids ; but they are 



often wanting or rudimentary, and they require no further 



consideration here. 



As regards the distribution of the Fedunculated Cirripedes 

 in time, until recently no member of the family was certainly 

 known to have existed in the Palaeozoic period. Dr Henry 

 Woodward, however, has described a very interesting form 

 from the Upper Silurian rocks, under the name of Turrile- 

 X>as (fig. 200, A). In this singular fossil the peduncle was 

 furnished with intersecting rows of plates, as in Loricula. 

 These plates, when detached and occurring in an isolated 

 condition, are not unlike the shells of certain of the Ptero- 

 pods, and fragmentary specimens may be, and have been, 

 taken for Chitons. The genus Turrilepas is identical with 

 the Plumulites of Barrande, and species have been now de- 



Fig. 199. Capitulum of a Pedunculatod Cirripede. 

 a ' Ter & im '> & > Scutum; c, Carina; d, Upper latus ; 

 e> Cariuo-latus ; /, Rostrum; g, Sub-rostrum; h, 

 Ros tral latus ; t, Infra-median latus ; fc, Sub-carina. 

 (After Darwin.) 



