OH the North Coast of Cornwall. 149 



Climatius, sp. (PI. VIT, Figs. 9, 10.) 



The only example is a fragment of a compressed spine, 9 ram. in 

 width and 2 mm. in thickness ; the exposed surface is jet-black ; it 

 shows stout, straight, longitudinal ribs, of which there are eight in 

 the width of the spine. The upper edge of the ribs is, in places, 

 tuberculate, and on one side of each there are, at intervals, blunted 

 processes which reach across the interspace between the ribs so as 

 to form elongate hollows, now filled with matrix. According to 

 Dr. Smith Woodward the structure of this spine resembles that of 

 the spines of the genus Ciimatitis, Ag., which has a dermal spine 

 in front of each fin except the caudal. 



The specimen figured is from Watergate Bay, The genus occurs 

 in the Lower Old Red of Forfar, Hereford, and Worcester, and in 

 the Lower Devonian of New Brunswick. 



The occurrence of the remains of Pleraspis, PhJyctfeuasjns, and 

 Climatius in the same series of shaly strata at Watergate Bay and 

 Bedruthan Steps derives significance from the fact, brought to ray 

 notice by Dr. Smith Woodward, that in other regions of Western 

 Europe and Eastern North America where these three genera are 

 present, they characterize the geological horizon of the Lower Old 

 Red Sandstone or the Lower Devonian. It may therefore be 

 reasonably assumed that the rocks on the North Cornish coast in 

 which they are found likewise belong to the same geological period. 



The following descriptions of Pterocomis minis, n.sp., and Pleura- 

 dictijiim, sp., have been contributed by Dr. G. J. Hinde, F.R.S. : — 



Family HYOLITHID^E, Nicholson. 



Genus Pteroconus, Green (^ Nereitopsis, Green). 



Pleroconus mirus, sp. nov. (PI. VII, Figs. 1-1.) 



Shell conical, compressed, straight; in transverse section round 

 or elliptical, on both sides with small shelly flap or fin-like 

 extensions disposed at regular intervals from the basal point to 

 the summit aperture. A longitudinal rod or thickening of the shell 

 enclosed within the cone. The outer surface with an ornamentation 

 of transverse lines of o-rowth follovvin<>; the contour of the summit, 

 and at intervals with stronger raised lines connected with the lateral 

 processes. No operculum has been observed. 



This description is based on the characters shown by a number 

 of specimens collected by Mr. Howard Fox at Bedruthan. The 

 fossils are exposed on the surface of a bluish or claret-tinted shaly 

 rock as they have been naturally weathered out ; in some tlie shelly 

 exterior of the test with its ornaraentation is visible, whilst in others 

 the interior of the cone has been laid bare. The forras are to some 

 extent compressed in the shaly rock, and only the surface weathered 

 in relief can be studied. The test is now of a brownish or reddish- 

 brown tint, owing to the replaceraent of the original shell by sorae 

 compound of iron ; the interior is now generally filled with the 

 shaly matrix. Only exceptionally are perfect specimens met with ; 



