152 Howard Fox — Devonian Rocks and Fossils of CovnicaU. 



ten large corallites in what appears to be a full-sized coralluni, 

 with smaller corallites ia the angles between the larger. The 

 corallites range from 5 to 9 mm. wide, their average diameter is 

 7 mm. They are polygonal or rounded in outline, shallow, the 

 walls are relatively thick and apparently vesiculai", showing small 

 irregular interspaces on their weathered margins. There are 

 indications of pores passing through the walls near the base of the 

 corallites and communicating with the exterior, but it is uncertain 

 if the corallites were directly connected with each other by mural 

 pores. A few blunt spines are present in the lower portion of the 

 corallites, but there are no indications either of tabulasor septal strise. 



Examples of this form are by no means rare, but they are all 

 very poorly preserved, and but little more than their upper surfaces, 

 slightly projecting from the bluish shaly rock, can be distinguished. 

 Their walls have been replaced by a mineral which gives a very 

 slight reaction with acid. So far as comparison is possible, the 

 form to which they are nearest allied is P. granuli/era, Schliiter 

 (Anthoz. d. rhein. Mittel-Devon. Abhandl. der geol. Landesanst., 

 vol. viii, 1889, p. 361, pi. iv, figs. 5-8), from the Middle Devonian 

 of the Eifel. According to Mr. C. W. Peach, P. problematicum, Goldf., 

 also occurs in abundance at Polruan and other localities in Cornwall 

 (Trans. Eoy. Geol. Soc. Cornw., vol. ix, p. 52), but I am unaware if 

 this determination has been confirmed. 



It seems desirable not to give a specific name to the present form 

 until better preserved specimens have been obtained. It is found 

 at Porthcothan, Porth Mear, and Lower Butter Cove. 



EXPLANATION OF PLATE YII. 



Fig. 1. — Pteroconiis mirus, Hinde, sp.n. Sho'n'uig the exterior siu'face of a fairly 



perfect specimen, weathered out on the surface of a shaly rock. Natui'al size. 



Lower ? Devonian : Bedruthan Steps, North Cornwall. 

 Fig. 2. — The same. An imperfect specimen from the same locality, the exterior 



surface shown in the portion above the line of jointing, and below this the 



interior of the cone with the lateral processes are exposed. Natural size. 

 Fig. 3.— The same. A part of Fig. 2, enlarged three diameters, showing the 



longitudinal rod within the cone and the striation of the lateral processes. 

 Fig. 4. — The same. An imperfect specimen showing in the middle portion the inner 



rod, exposed by the weathering away of the shell. Natural size. From 



Bedruthan. 

 Fig. 5. — PhJyctceyiaspis, sp. A fragment of a plate weathered out on a surface of 



shale. Natural size. From the Lower Devonian of Watergate Bay, North 



Cornwall. 

 Fig. 6. — The same. A portion of Fig. 5, enlarged ten diameters to show the 



tubercles, one of which is hollowed out. 

 Fig. 7. — Pteraspis Cornubica, McCoy, sp. An imperfect shield-plate, showing the 



striiB and lines of growth. Natural size. From the Lower Devonian at 



Watergate Bay. 

 Fig. 8. — The same. A portion of Fig. 7, enlarged five diameters. 

 Fig. 9. — Climatius, sp. A fragment of a spine, showing the strongly marked ribs 



with their lateral processes. Natural size. From Watergate Bay. 

 Fig. 10. — The same. Part of Fig. 9, enlarged five diameters. 

 Fig. 11. — Pleurodictyum, sp. The upper surface of a specimen, partly weathered 



out of bluish shale. Natural size. From the Lower Devonian at Porth- 



cothan. North Cornwall. 



