SCALPELLUM. 43 



13. ScALPELLUM TUBERCULATUM. Tab. I, fig. 10. 



S. valvarum lineis tenuibus, tuber culatis, elevatis, ab apice radiantibus: carina tecto 

 transverse leniter arcuato, et parietibus striatis: scuti umbone prope in medio marc/inis 

 occludentis posito, costis duobus ab umbone ad ant/ulum basi-lateralem, et ad basalis marginis 

 medium decurrentibus. 



Valves, with fine, tuberculated, elevated lines, radiating from their apices : carina, with 

 the roof in a transverse line, gently arched, and with the parietes striated : scutum, with 

 the umbo placed nearly in the middle of the occludent margin, with two ridges running 

 from the umbo to the baso-lateral angle and to the middle of the basal margin. 



Chalk Detritus. Charing, Kent. Mus. Harris. 



Through the kindness of Mr. Harris, I have examined several valves, which I believe 

 to belong to the same species : the specimens were found in the chalk detritus, and, 

 therefore, may have come from the Upper or Lower Chalk or Chalk- marl ; but more 

 probably from the Upper Chalk. With respect to the scuta and terga I have scarcely any 

 doubt, from certain peculiarities, that they belonged to the same species ; but with regard 

 to the most important valve, the carina, I cannot feel quite so certain : when the latter is 

 so held, that the parietes are not visible, it has a very close general resemblance to the same 

 valve in PoUicipes rigidus. In the carina, the present species comes closer to S. arcuatum 

 than to any other species ; in the other valves, especially in the singular scuta, it departs 

 widely from that and all other known fossil forms, with the exception of S. (?) creta, of 

 Denmark. All the specimens which I have seen are small ; the carina being "2 long, and 

 the terga less than -15 of an inch in length, in the largest specimens. 



consequence of this, the lines of growth make a different angle, on the opposite sides, with this ridge : 

 as the valve has been somewhat worn, it is possible that the carinal margin may have been more abraded 

 than is apparent. Internally, it is seen that a considerable portion of the upper part of the valve projected 

 freely ; beneath this, the inner surface is slightly convex, but smooth, and though the shell has been much 

 worn, I doubt whether there ever existed ridges, as on the internal surface of the upper part of the terga 

 in S. arcuatum, to which valve this presents a close general resemblance. Length of tergum (when 

 perfect), \'2 of an inch. 



Carinal Latus (fig. 8, e, f) ; amongst the fossils from Kopinge (at which place the same species are found 

 as at Kjuge), there is a valve, which I believe to be a carinal latus of a Scalpelluni, and which, from its 

 longitudinal ridges, more probably belonged to the present than to any other species : from its peculiarity 

 it is in any case worthy of description. In form it is a segment, somewhat less than a quarter, of a circle ; 

 of this segment, nearly half (I believe the upper half) has its end or circumferential margin much 

 hollowed out, and its surface smooth : the other half has its periodical growth-ridges very prominent, 

 and these are crossed by a few slight longitudinal ridges. One of the lateral sides (the upper, I believe,) 

 is reflexed so as to form a prominent ledge ; the other side is slightly inflected. 



