78 FOSSIL CIRlllPEDIA. 



the breadth varies with respect to the height ; sub-carinated, shghtly bowed outwards or 

 backwards, and therefore, in the opposite direction to what is usual ; but the amount of 

 curvature varies much : roof arched, inflected along the lateral edges ; basal margin 

 protuberant, formed of two curved lines meeting each other at an angle of above 90°. 

 The lines of growth on the inflected lateral edges, curve slightly downwards {h), and then 

 just perceptibly upwards ; thus, no doubt, making the heels or two basal corners slightly 

 prominent. Internally, within the lateral edges (having the lines of growth as just described), 

 and separated from them by a distinct indentation, there is on each side {h) a narrow ridge, 

 widest at about the middle of the upper half of the valve, and marked with longitudinal 

 lines of growth ; these internal lateral ridges have evidently been (as seen in the section) 

 (g?) formed during the filling up and thickening of the upper, solid, outwardly bowled 

 part of the carina, which ])art, no doubt, projected freely. The lower part of the carina (c) 

 is deeply concave. Roemer describes the exterior surface of the shell as marked with 

 alternate finer and stronger concentric lines, and rarely along the edges alone with longi- 

 tudinal lines. 



The specimens from the Upper Greensand of Warminster differ from the foreio-u 

 specimens, in being very slightly bowed inwards instead of outwards, and in having a 

 more tapering form ; but it is precisely in these two respects, that the four foreign specimens 

 seen by me vary to a considerable extent ; therefore, at present, the English specimens 

 must be ranked under P. Bronnii. 



These valves certainly differ considerably from any other known ones : the slight out- 

 ward bowdng of the carinae from the Hils-conglomerat is their most conspicuous cha- 

 racter, and was present in the four specimens seen by me, and I presume, from Roemer's 

 description, is general. In recent species, however, the degree of curvature of the carina 

 is often variable : in P. spinosus, I have seen some specimens with the upper part of the 

 carina even outwardly bent, and others with it straight. The manner in which the upper 

 part of the valve has been filled up, having two lateral, inwardly projecting ridges, is unhke 

 any other species, and is the main specific character : the carinae of Scalpellum soUdulum and 

 of the var. cylindraceum. of 8. maximum make the nearest approach to this structure. From 

 such scanty materials I will not pretend to say to what species this is most closely allied. 



22. POLLICIPES PLANULATUS. Tab. IV, fig. 11. 



PoLLiciPES PLANULATUS. J. Morris. Annals of Nat. Hist. vol. xv, 1845, pi. 6, fi". 2. 

 — — J. Sowerbij. Miu. Couch., pi. Q,A7, fig. 2. 



P. tergis subrhombicis, latis, lavibus, apice basali late truncato, latitudine dimidium lon- 

 gitudinis margi/ds occludentis aquanfe ; apice basali truncato unguium rectum cum margine 

 scutali formante ; parte superiori viarginits scutalis cuspidem latam, rotundatam, IcEviter 

 prominentcm fonnante. 



