Morpholoijy of some Cretaceous Cirripedes. !^G9 



PoUicipes filosun, "Withers, 



,, fffit/i if/en sis, II. B. Geiiiitz, 



„ glnher, F. A. Roemer. 

 Scalptlhon longissimum, Withers. 



,, oppoliense, Leonhard. 



PulUcipes striutus, Darwin. 



,, ,, var. y>flMCJ5/rifl/M5, II. Woodward. 



Albian : 



Pollicipes unguis, J. de C. Sowerby. 

 ,, iinhricatus, Withers. 



Neocomiaii : 



FoUicipes hronni, F. A. Roemer. 



All the species enumerated above were founded on detached 

 valves, and in the case of P. unguis and 1'. glaher only has 

 any number of valves been found in their natural position. 

 All the valves have apical umbones. The carina, where 

 known, is simple in structure, and by this I mean that it is 

 not separated by means of ridges or alteration in direction 

 of growth-lines into tectum, parietes, and intraparietes, for 

 these parts are not defined, and the valve is strongly convex 

 to flatly-arched in transverse section. The scutum, in addi- 

 tion to the apico-ljasal ridge, has a second ridge, more or less 

 prominent in the several species, extending from the apex to 

 about the middle of the basal margin, and like the Arcoscal- 

 pellids has a comparatively wide tergo-lateral portion, which, 

 iiowever, varies in width in the several species. The tergura 

 is not in any way peculiar, but the valve is usually rounded 

 and protuberant along the occludent margin, followed by a 

 rather wide furrow extending to the scutal margin. The 

 upper latus is rather simple, and forms almost an equilateral 

 triangle, with the scutal side a little longer than the tergal, 

 but with no elaboration of structure, such as the truncation 

 of the basal angles and the growth-lines upturned at the 

 sides. Of tiie lower latera, the carinal latus is the valve 

 more frequently found, and this is subtriangular to oblong 

 in shape, and is about twice as large as the rostral and 

 inframedian latus, which are almost exactly similar in shape 

 and size. The rostrum is subtriangular, large, and wide, 

 usually with an apico-basal ridge. The peduncular plates 

 are large, with a smooth, narrow, inwardly-projecting ledge ; 

 on the inner margin of this ledge in the plates belonging to 

 P. unguis there is a median elliptical socket, but I have not 

 noticed such a feature in the numerous peduncular plates 

 that I have seen of P. ghiber. 



