NO. 2297. BRACHIOPOD OENUS PLATYSTROPHIA—McEWAN. 419 



There are three plications in the sinus and four on the fold in the 

 neanic stage of development. In some specimens this number is not 

 increased during later growth. Some specimens show that in the late 

 neanic and ephehic stages plications are added by intercalation on the 

 slopes of the sinus and bifurcation of the outer plications of the fold ; 

 or there may also be implantation in the sinus next to the primary 

 plication and bifurcation of the median plications on the fold. 



The lateral slopes of the brachial valve are convex, those of the 

 pedicle valve are flatly concave. They are occupied by eight and nine 

 closely spaced, round plications. 



This species has the oval form and low spreading miiltiplicate sinus 

 of PI oty strop]} ia dffianfvln, new species of tlie Trenton limestone. It 

 is easily distinguished from that species by the ventricosity of the 

 valves and by the shallowness of a fold and sinus next to the beak. 



Measvmnenfs. — S mm. along the hinge line, 12 mm. wide across tlie 

 middle, 8 mm. high, 7 mm. thick, 6.2 mm. sinal width, 3.5 mm. sinal 

 depth, 1 mm. fold depth. 



Occurrence. — Maysville group: Corryville beds, Morrow, C'incinnati, 

 etc., Ohio. 



Plesiotypes.—Ciit. Nos. 41166, 48610, U.S.N.M. 



PLATVSTUOFHIA CORKYVILLENSIS, new species. 



Plate 43, figs. 27-29. 



In the Corryville beds at Cincinnati, Ohio, is found a small, trans- 

 verse, ventricose form with a long hinge line, a low-spreading fold, 

 and broad, shallow sinus. The fold and sinus are occupied by three 

 and four subequal ]>lications and the lateral slojies by eight and nine 

 rounded, closely spaced plications. The slopes of the brachial valve 

 are convex, with a slight concavity next to the ("ardinal extremes; 

 those of the pedicle valve are flatly concave. The fold rises very 

 little above the general convexity and the sinus is only moderately 

 deep. 



Measure^nents. — 14 mm. along the liinge line, 18 mra. wide across 

 the middle, 9 mm. high, 7.5 mm. thick. 6.4 mm. sinal width. 8.2 mm. 

 sinal de])th, 1 mm. fold height. 



OccuiTence. — Maysville gToup: CorrjviUe beds; Cincinnati, Ohio. 



Cotypes. — Cat. Xo. 65926, U.S.N.M. 



PLATYSTROPHIA SUBLATICOSTA, new species. 



Plate 45, figs. 17-19. 



At several localities a s])ecies was found which resembles Platy- 

 sirophia laticosta, but which differ from that species in possessing a 

 low fold throughout its life history, in being thinner and less gibbous, 

 and in having sti'onger lateral plications of the fold and sinus. 



