lo The Paleontologist. [Sept. 14, 



The large canals in this fossil do not accord with Mr. Billings' Generic description of 

 Trackyum, but in other respects it is so much like it as to seem best to place it in that 

 Genus, provisionally at least. 



Position and locality — Upper Silurian, Clinton Group, Clinton Co., Ohio. 



GENUS STROMATOPORA, (De Blainville ) 



Stromatopora lunata. (sp. nov) (James.) (Lunata, crescent-shape, in allusion 

 to the curved lamellae in vertical section.) Sarcodeme, composed of thin lamellae. A 

 vertical section shows each lamella in a general horizontal direction, in a succession of 

 variable, low, sub-lunate arches about y^ a line in length united at each end by either very 

 delicate vertical dissepiments, or resting upon the lamella below; about 5 lamellae in the 

 space of one line vertically, including the interspaces, which are wider, generally, than the 

 thickness of the lamellae. Oscula-like canals, from i to 3 lines in diameter, at very irregu- 

 lar distances apart, passing through, apparently, the body of the fossil. The lamellae 

 curve sharply upward all round the oscula, so as to be nearly or quite vertical at the upper 

 aperture. 



A polished under surface shows the lamellae, at one point, where they seem to be out 

 of the horizontal direction, as arranged in curved parallel lines with numerous very fine 

 dissepiments at various angles and distances apart. 



The specimen (a fragment) from which this description is made, is sub-circular in out- 

 line, about 4 inches in diameter and 3^ of an inch thick in the middle, sloping gently off 

 to a thin edge all round ; the sloping surface weathered so as to give to the edges of the 

 lamellae somewhat the appearance of shingles on a roof, one overlapping the other. 



Position and locality — Upper Silurian, Niagara Group, Clinton Co., O. 



Stromatopora Hindei. (Nicholson.) A specimen from the Niagara rocks of Clin- 

 ton Co., O., resembles Prof. Nicholson's figures of this species, in his Report upon the 

 Paleontology of the Province of Ontario, 1874, except that it is much larger and more mas- 

 sive, the upper surface more regularly striate, (due, perhaps, to weathering) and fewer 

 oscula, but the vertical section and other features bear a close resemblance to that species. 



GENUS LYELLIA, (Milne-Edwards.) 



Lyellia Striata, (sp. nov.) (James.) Corallum, a horizontal expansion of variable 

 thickness; upper surface undulating and covered with rather coarse sinuous striae. 

 Tubular mammelae-form prominences, with broad bases, sometimes in contact (the bases) 

 irregularly distributed over the surface, varying from 2 or 3 lines to over ^ an inch apart, 

 measuring from center to center of the tubes. A vertical section shows the tubes passing 

 in an oblique direction through the coral, with 3 or 4 vertical dissepiments, between 

 which and the outer wall are numerous closely set tabulae. Apertures of the tubes in 

 the center of the prominences circular, and about one line in diameter, rounding in at the 

 margins, forming a shallow cup, in the center of which is a solid column-like substance, 

 raised to a level with the highest part of the prominence, and occupying about half of the 

 aperture ; this central column seems to be formed by the drawing together of the verti- 

 cal dissepiments at the top. 



From 12 to 20, not clearly defined (in the example examined) septa are shown, which 

 do not extend below into the body of the tube. 



The coenenchyma consists of undulating laminae which are drawn closely together in 

 places, appearing like a solid mass, then suddenly expand by regular curves and divide 

 into many parts in an irregular manner, some of them very thin, all wavy or undulating 

 in their horizontal course. At the points where the plates unite with the tubes they curve 

 first upward then round over in an arching manner to the horizontal direction. 



The specimen from which this description is made is a fragment about 2x3j^ inches of 

 variable thickness, y^, an inch or a little more at the thickest part. It appears as if the 

 species may have spread over considerable horizontal surface, and have been, perhaps, 

 more massive in some cases. Under side not observed, it being attached to a rocky 

 substance. 



Another specimen, apparently the same species, is much larger and more massive and 

 destitute of the upper surface striae ; the under surface is shown on this with the bases of 

 the tubes projecting; this fragment is 3x8 inches in size, and at one place over i|^ inches 

 thick. 



Position and locality — Upper Silurian, Niagara Group, Clinton Co., O. 



