DESCRIPTIONS OF INVERTEBRATE FOSSILS. 5<) 



ends with the similarly attenuated supero-anterior ends of 

 the radial costa?, fornnni,' with the latter, at the place of meet- 

 ing, a series of beakward-pointed V-like angles. 



^f('asKrenlellfs.— (Approximate.) Height 70, breadth 10, 

 length 100-105 mm. 



Occurrence. Several molds of this species were found 

 by Mr. J. T. Munson aud the writer in the Choctaw lime- 

 stone, with Ostrea quadrujjh'catd, Exo<jijra ariciina, Tcrc- 

 hratella wacoensis, etc., on the Pawpaw c-reek bluffs east and 

 southeast of Denison, Texas. For an example from Cooke 

 county, Texas, showing the shell itself and the major part of 

 both valves, the writer is indebted to Mr. G. H. Ragsdale, 

 after whom the species is named. 



A loan-collection now in hand contains one example of 

 this beautifully and uniquely marked species from a county 

 in Texas south of the Red river tier, but it is not now pos- 

 sible to ascertain its exact source. 



As all of the specimens of this fossil that the writer has 

 seen are more or less imperfect, there remains some doubt as 

 to the generic position. But the species is so striking and 

 unique in the character of its ornamentation that there will 

 rarely be difficulty in recognizing it, even in the imperfect 

 specimens in which it commonly presents itself. 



HOMOMYA WASHITA, sp. nOV. 



Shell large, curved-oblong, closed or nearly closed an- 

 teriorly and closed along the dorsal margin back of the beaks, 

 obliquely truncated and gaping posteriorly, the breadth 

 usually a little greater than the vertical dimension from 

 hinge-margin to ventral margin, the length ecjual to some- 

 what more than one and a half times the breadth, the greatest 

 breadth being about half way between the beaks and the mid- 

 region: beaks nearly terminal low, swollen, obtusely tangent, 

 their bases long in the direction of the length of the shell 

 and rising at a very low angle from their posterior origin to 

 their rather l)roadly .rounded summits: surface marked only 

 with concentric growth-lines and undulations, and sometimes 

 showing distally two or three broad growth-zones or stages. 



