ON CEPHALASPIS AND PTERASPIS 50S 



Roemer gives an account of a fossil, which he refers to the SepiadcB, 

 under the name of Pal<^oteuthis. Whether this body is or is not 

 a Cephalopod, is a point I will not enter upon here ; but Roemer in 

 referring to Kner's Memoir, expresses the opinion that the Pteras- 

 pides are Crustacea. 



Mr. Salter and myself described two new species of Ceplialaspidce 

 allied to C. Lloydii ( Ag.), in a note ^ appended to a paper read before 

 this Society by Mr. Banks, in December 1855. Without acceding 

 to Kner's views respecting the zoological affinities of such Cephalas- 

 pids, we adopted his name. The facts to be detailed in the present 

 paper will, I believe, fully justify this step ; and I shall hereafter speak 

 ■of C. Lloydii and its allies under the generic name of Pteraspis. 



Professor Pander ^ has recently described two Silurian species of 

 Cephalaspis {C. verrucosus and C. Sckrenckii) both from Rootsiktille. 

 The former somewhat resembles C. oniatus (Egerton), having a 

 highly ornamented and tuberculated upper surface. In the broad 

 tuberculated antero-dorsal plates, separated from the head by a suture, 

 it foreshadows Auchenaspis, Eg. C. Schrenckii has hexagonal orna- 

 mented plates upon its disk. 



Professor Pander appears to think that the margins of the disk re- 

 present jaws, being led to this conclusion, apparently, by their produc- 

 tion into short quadrate serrations, which he regards as teeth. Sections 

 ■of these " jaws '' and " teeth," examined microscopically, exhibited 

 " a homogeneous base, in which clear and dark cells of the most 

 various forms — rounded, elongated, and angular, with fine radiating 

 branches, lay scattered, and were frequently disposed in concentric 

 layers, where a tubercle rose above the general surface. Although 

 they have not the same regular form as ordinary bone-lacuna; (such 

 as occur in Pterichthys and Coccosteus), yet they can hardly be 

 called by any other name. The very thin narrow teeth, closely united 

 with the margins of the jaws, and coalescent with them, have a porous 

 basis, and shining broad, sharp upper and lateral edges. If both 

 surfaces are carefully rubbed down, the basis is seen to consist for 

 the most part of a homogeneous transparent mass, full of small dark 

 cells, from which the very fine tubuli radiate in all directions, branch 

 •out, unite with the neighbouring ones, and by their many anasto- 

 moses form a most complex network. Towards the shining surface, as 

 well as anteriorly and posteriorly — at least, certainly, towards one sur- 

 face — the cells cease ; the tubuli, winding irregularly in the base, take 

 a straight course, and ascend apparently with an enlarged diameter, 



' 'Quart. Journ. Geol. Soc' vol. xii. p. 100. 



2 ' Monographie der fossilen Fische des Silurischen Systems,' 1856. 



