POLLICIPES. 77 



' Species aliquot quas, sctdis incognitis, mictores a valvis insignihm nomindrunt, luc pro 



tempore solummodo iterum describmitur. 

 Species named by authors from remarkable valves, but their scuta being unknown are 



here only provisionally re-described. 



21. POLLICIPES BRONNII. Tab. IV, fig. 10. 



PoLLiciPES BRONNII. F. Roemer. Verstein. Norddeutschen Kreidegebirges, p. 103, 

 Tab. xvi, fig. 8, 



P. carina Icevi, suhcarinatd, margine hasali arcuato et turgido ; totd valod vel extrorsiim 

 arcuatd vel pane redd ; interne, costis duabus elevatis ad utrumque latiis partis superioris 

 lihere prorninentis. 



Carina smooth, subcarinated ; basal margin arched and protuberant ; whole valve 

 either outwardly bowed or nearly straight. Internally, the upper, freely-projecting portion, 

 has on each side a prominent ridge. 



Upper Greensand, Warminster, England. Mus. J. Teunant. Hils-conglomerat bei Essen. Mus, Univers., 

 Copenhagen . 



My materials consist of some specimens lent me by the kindness of Professor Steen- 

 strup ; they consist, as well as those described by Roemer, only of the carina ; their sur- 

 faces are considerably worn. The Hils-conglomerat of Essen is considered by Roemer as 

 the equivalent of one of the lower beds of the Lower Greensand ; but recently MM. 

 Saemaan and Geinitz have shown that it really corresponds with the Upper Greensand. 

 Professor Tennant has lent me a single broken carina from Warminster, which cannot, in 

 our present state of knowledge, be specifically separated from the typical continental 

 specimens, though, as we shall see, slightly differing from them. 



I will first describe the foreign specimens. 



Carina (Tab. IV, fig. 10) strong, massive, triangular, about twice as high as broad ; but 



what bowed inwards ; basal margin not in the least protuberant ; not carinated, but steeply convex, so that 

 a section of the base (!>) has steeper sides than a semi-circle. 



Diagnostic characters. In comparing the scuta of P. ri(/iiJ>ts, fallax, and elegans, the latter can be at 

 once distinguished from P.faUax by the ridge running from the apex having perpendicular or wall-sides, 

 and by the straightness of the basal margin ; from P. rigidus, by the ridge being much broader ; P. fallax 

 differs from both, in the absence of longitudinal striae. In the terga, P. eleyans differs from both P. riyidus 

 and fallax, in the ridge running from the apex to the basal angle being straight, and in its greater breadth, 

 and likewise in the shortness of the upper carinal margin. The terga of P. fallax differ from the homo- 

 logues of the other two species, in the ridge connecting the upper and lower points, not having perpendicular 

 sides. 



