442 DE. G. J. HINDE ON NEW FOSSILS [Aug. 1 896,, 



examples of the species the corallum has somewhat the form of a 

 rifle-bullet : its basal end is conical and evenly rounded, with no trace 

 of attachment ; the outer surface has longitudinal ridges, the same 

 as in the compound forms ; and the wall, both of the sides and base, 

 is similarly traversed by direct mural pores (PL XXIII. figs. 7 & 8). 

 The calice is more directly conical than the outer form, so that the 

 basal portion of the wall is thicker than the upper part, and the 

 mural pores opening on the exterior through this thickened base 

 have somewhat the character of canals (PI. XXIII. fig. 10). In no 

 example yet discovered are there more than four corallites present. 



The microscopic structure of the wall of this species is of radiating 

 crystalline fibres, like that of corals generally (PI. XXIII. fig. 15) r . 

 and in its present condition of preservation it is closely similar in 

 appearance under the microscope to a thin section of Favosites, sp. y 

 from the Devonian, with which I have compared it. The mural 

 pores also are comparable with those of Favosites and Pleurodictyum. 

 Neither epitheca nor ccenenchyma is present, and there is no indi- 

 cation of tabulae or of solid non-perforate tissues filling the base of 

 the calices. 



The diameter of the normal corallum with four corallites ranges 

 from 10 to 15 mm. ; in length the individual corallites vary 

 between 4 and 6 mm., and in width, at their summits, between 3 

 and 4-5 mm. There are from 20 to 30 longitudinal ridges, and a 

 corresponding number of rows of mural pores, in a corallite. 



The present species, which I propose to name P. humilis, is dis- 

 tinguished from P. cuneiformis, Haime, the typical species, in its 

 general form and the size and disposition of the corallites ; the 

 external ridges, moreover, are of a coarser character, and they are 

 more regularly arranged. The resemblance to P. (Splienopoterium) 

 obtusa, Meek & Worthen, sp., 1 is less apparent, for this latter form 

 is considerably larger, its walls are relatively very thick, and the 

 corallites are wide and openly conical. Palceacis (Sphenopoterium) 

 enormis, Meek & Worthen, 2 and its variety depressa, moie nearly 

 correspond in size with the present species, but the surface-striae 

 are said to be broken up into irregular granules. Owing to the 

 brief description of this form, no nearer comparison is possible. 

 For reasons given below, I consider that P. humilis has no generic 

 relations with (Palceacis) Hydnopora? cyclostoma, Phillips. 3 



Distribution. — Fairly common in shale or mudstone associated 

 with limestones and chert exposed in the banks of the River Hodder, 

 below Stonyhurst College, Lancashire. According to Mr. R,. H. 

 Tiddeman, 4 the rocks belong to the Southern or Bowland type of the 

 Carboniferous Limestone of Lancashire, and come in between the 

 Clitheroe Limestones and the Pendleside Limestones. Collected by 

 the Rev. G. C. H. Pollen. 



Also in soft decayed shale of the Lower Culm Measures at Overton 



1 Proc. Acad. Nat. Sci. Philad., Oct. 1860, p. 447. 



2 Geol. Surv. Illinois, vol. ii. (1866) pi. xiv. figs. 1 & 2. 



3 « Geol. Yorkshire,' vol. ii. (1836) p. 202, pi. ii. figs. 9 & 10. 



4 Geol. Mag. 1894, p. 482. 



