1878.] The Paleontologist. 13 



GENUS PTERINEA. (Golpfuss ) 



p. Subqnadrata . (sp. nov ) (James.) Shell sub-quadrate in outline, oblique, 

 anterior wing short, posterior wing broad and extending scarcely beyond the margin of the 

 shell. Beak slightly projecting, umbro rather flat. Surface gently convex from the ante- 

 rior margin to a line passing in a direction with the obliquity of the shell from the car- 

 dinal line back of the beak to the margin, where it becomes suddenly depressed, shoulder- 

 like, from which line the posterior wing is spread ovi nearly flat. The margin is regu- 

 larly rounded from the slope of the anterior wing to the backward depression Surface 

 covered with rather prominent, sharp, slightly rugose, concentric lines, which are finer 

 and more crowded on the posterior wing than on other parts. Right valve and interior 

 not observed. 



This species bears a slight resemblance to Conrad's description and fig. of Pt. [Ai'ictda) 

 insueta, but differs materially in the marked features of the sudden depression and broad 

 flat surface of the posterior wing, which is less extended, and in the more crowded concen- 

 tric lines and absence of longitudinal radiating striae; also in the general outline of the 

 shell. 



The specimen from which this description is made, is about '/^ of an inch, measuring 

 from beak to front margin, and the same from the point of the posterior wing to the ante- 

 rior margin. 



Position and locality — Cincinnati Group, Clinton Co., Ohio. 



RKMAEK.S ON CONSTELLAKIA ANTH KLOIDKA. (Hall) 



This beautiful species of fossil coral is found in abundance, and in a marked degree of 

 perfection in the Lower Silurian rocks at Cincinnati. And, although thousands of speci- 

 mens (fragments) have been collected here, it is safe to say that a single entire corallum 

 has not yet been found. 



Different examples are of a great variety of shapes, — palmate-tligitate, flabellate, sub- 

 frondose, cylindrical and intermediate forms, and some approaching to amorphous masses ; 

 the upper and outer branches are more delicate than the others — not so thick and robust 

 — the evidence that they were the upper and outer branches, is, the calices extend round 

 and over the smaller ends — no fracture. 



A complete or entire corallum must, apparently, have been of considerable size; prob- 

 ably a foot or more in height and as much laterally. (Prof. Nicholson says — Ohio Pal. — 

 a height of 2 inches or more.) 



The "stars" differ more on different specimens than the shapes of the cylindrical and 

 flattened branches and frondose expansions. On the outer and upper branches of various^ 

 forms, the rays are sometimes elevated into sharp spur-like points, from which they are 

 graded down on different examples — becoming less and less prominent until they fall 

 to a level with the general surface, and then sink below the surface — depressed 

 instead of ^fo^«/^a' stars. The number of rays to the different "stars" varies from 5 or 6 

 to 30, some of them appearing like elevated ridges — 2 or 3 lines in length — with the rays 

 like spur projections on each side and end; others extend all round tfee cylindrical 

 branches appearing like annulations. 



Different degrees of weathering — they are found in all stages — causes quite different 

 surface appearances, but not the differences in the elevated and depressed "stars" and 

 their outlines. 



Prof. Nicholson's species, pohstomella^ seems to be one of these variety forms. 



The probabilities are, that on the base and lower branches of this cor-Al the stars varied 

 in shape and prominence from those on the upper and outer parts. We have illustrations 

 of this character in some of our other associated corals and Polyzoa. For example, 

 Chaetetes gracilis, James; Ch. O' Nealli, James; Helopora dcndHna, James, and various 

 species of Piilodictya, and others that might be named ; the cell apertures on the base and 

 upper parts being entirely different. And on different parts of the same fragment, or stem. 



