24 FOSSIL CIRRIPEDIA. 



3. ScALPELLUM FossuLA. Tab. T, fig. 4. 



PoLLiciPES MAXTMUS. J. Sowcrby. Min. Conch. Tab. 606 (a tergum), fig. 3, 



S. carina intra-parietibus instructd ; tecto utrinque costis magnis^ tumidis, superne 

 planatis, marginato; margine basali obtuse acuminato. Lateribus superioribus quinque- 

 lateralibus; costis duabus modicis ab apice ad marginem basalem continuatis. 



Carina, having intra-parietes, with the tectnm bordered on each side by large, pro- 

 tuberant, flat-topped ridges ; basal margin bluntly pointed ; upper latera five sided, with 

 two sUght ridges extending from the apex to the basal margin. 



Upper Chalk. Norwich; Northfleet, Kent. Mus. Fitch, J. de C. Sowerby, Wetherell. 



General Remarks. My materials consist of two specimens, belonging to Mr. Fitch, 

 most kindly lent me for examination ; in which, taken together, the scuta, terga, carina, 

 upper and carinal latera, are seen almost in their proper places. In Mr. J. Sowerby's 

 collection there is a single scutum, also, from Norwich. From analogy with the eocene 

 S. quadratum and the recent 8. rutilum, I have little doubt that there were only three pair 

 of latera ; and that, probably, there was a rostrum. "With respect to the exact position of 

 the carinal latera, there is, as also in the case of the S. quadratum, some little doubt. 



Capitulum narrow, elongated, probably composed of 12 valves, which are moderately 

 strong, and apparently closely locked together. The length of the capitulum in the largest 

 specimen was I'l of an inch. 



Carina (fig. 4, c, g, h) strong, moderately bowed, extending far up between the terga, 

 almost to their upper ends ; rather narrow throughout, gradually widening from the apex 

 to the base ; lines of growth plain ; no portion projects freely. The tectum or central 

 portion is slightly arched, subcarinated, and bounded on each side by flat-topped, pro- 

 tuberant ridges : the tectum terminates downwards in a blunt point (the two margins 

 forming an angle of rather above 90°), which projects beyond the bounding ridges ; the 

 tectum and the two bounding ridges all widen gradually from the apex towards the 

 base. The parietes are channelled or concave; they do not extend so far down as 

 the ridges bounding the tectum. In the upper half of the carina, we here first see 

 the additional parietes, or intra-parietes, which appear as if formed subsequently to 

 the other parts, and let in between the ordinary parietes of the carina, and the terga. 

 It has been already shown, under S. magnum, that it is the intra-parietes produced 

 upwards, which causes in that and some other species the umbo of the valve to be sub- 

 central. 



Scuta (fig. 4, a,f) oblong, the basal margin only slightly exceeding half the entire length 

 of the valve ; valve strong, rather plainly marked with lines of growth ; basal margin at 

 nearly right angles to the occludent margin ; tergal margin separated by a slightly -projecting 



