536 D. K. Greger — N. A.merican Species of Etheridgina. 



selected for illustration, from the Fife specimens in hand, an example 

 attached to a fragment of gastropod shell, since this specimen shows 

 both valves, in their natural position, and other features in an 

 excellent manner. 



Etheridgina radicals (Winchell). (PL XIV, Figs. 4-8.) 



1866. Crania radicans Wiiicliell, Geo). Rept. Lower Peninsula of Michigan, 



Appendix, p. 92. 

 1890. Strophalosia radicans Beecher, Amer. Journ. Rci., vol. xl, p. 2-iO, pi. ix 



figs. 14-17. 

 1892. S. radicans Hall & Clarke Pala?ont. New York, vol. viii, pt. i, pi. xv5, 



fig?. 27-:)0. 



I have seen but three imperfectly preserved examples of this 

 species, from the limestones of the Hamilton (Devonian) from the 

 vicinity of Alpena, Michigan. Their condition is such that specific 

 characters are almost obliterated. Beecher and Hall & Clarke have, 

 however, given ample illustration of the characters of the species, 

 and figures of these authors are here reproduced. 



Etheridgina keokuk (Beecher). (PI. XIV, Figs. 9-11.) 



1890. Slrophaloaia Jceohik Beecher. Amer. Journ. Sci., vol. xl, pp. 24-1-5, 



pi. ix, figs. 18-24. 

 1892. S. keokuk Hall & Clarke, Palaaont. New York, vol. viii, pt- i,pl. xviia, 



figs. .5-7. 

 1914. S. keokuk Weller, Mississipj^ian Brachiopoda, Monogr. No. I, Illinois 



Geol. Surv., p. 145, pi. xviii, figs. 17-18. 



This species is fairly abundant in the Crawfordsville Shale 

 (Mississippian) of Indiana, most frequently found attached to 

 Platyceras and corals, also occasionally found on the columns of 

 crinoids, which are abundant in the shale. I have reproduced the 

 original figures of Beecher and one by Hall & Clarke. 



Etheridgina scintilla (Beecher). (PI. XIV, Figs. 12-14.) 

 1890. Strophalosia scintilla Beecher. Amer, Joui'n. Sci., vol. xl pp. 243-4, 



pi. ix;figs. lo-i:?. 



1892.- S. sciniilla Hall & Clarke, Pala!ont. New York, vol. viii, pt. i, pi. xvft, 



figs. .'',2-4. 

 1908. 8. scintilla Rowley, Missouri Bureau of Geo]., vol. viii, 2nd ser., p. 76^ 



pi. xvii, figs. 26-9. 

 1914. S. scintilla Weller, Mississijipian Brachiopoda, Monogr. No. 1, Illinois 



Geol. Surv., p. 144, pi. xviii, figs. 19-23. 



The youngest example of this species I have found is subcircular,' 

 and has a diameter of 0"4 mm., the brachial valve is gently convex, 

 hinge-line and beak very obscure. Specimens of TO mm. in 

 diameter are slightly transverse, with well-defined hinge-line and 

 less obscure beaks ; the brachial valve generally exhibits one or 

 two well-defined growth-lines. At this stage in the development 

 of the shell the pedicle valve is closely cemented to the host, the 

 hinge-line and beak only being raised above the level of the front 

 and sides However, upon reaching maturity, or ajDproximately 

 2'5 mm. in diameter, a trail begins to form by the abrupt upward 



