408 TRANS. OP THE ACAD. OF SCIENCE. 



Some New Varieties of Spirifer lineatus, Martin ; Spi- 



RIFER CAMERATUS, MortOtl / SPIRIFER KeNTUCKENSIS, 



Shumard ; Spirifer Leidyi, Norwood and Pratten ; 

 Spirifee increbescens, Hall, and Spirifer Keokuk, 

 HalL By G. C. Swallow. 



Spirifer lineatus, Martin. 



Although this fossil appears to be characteristic of the 

 Mountain Limestone of Europe, all the specimens in the Mis- 

 souri Collection, and indeed all the American specimens 

 which I have observed, came from the Coal Measures. Our 

 State Collection contains many specimens, which cannot be 

 distinguished, by the form, markings, or size, from those fig- 

 ured by Sowerby (Min. Con., Vol. IV., PI. 334), or from spe- 

 cimens before me from Ireland and Derbyshire. Like those, 

 our fossils have no concentric stria? on the transverse bands ; 

 and, like the Euro])ean specimens ah/>ve cited, the wider 

 forms usually have an obsolete sinus on the ventral valve, 

 which renders the margin slightly sinuous. 



Length, .95; width, 1.11 ; thickness, .68. 



This fossil is common in the Coal Measures of the Missis- 

 sippi Valley. 



Variety, perplexa, McChesney. 



Prof. McChesney has described what appears to be a small 

 variety of this fossil under the name perplexa / but I can see 

 only one or two slight differences. Tjfcie perplexa is usually 

 wider than long, while the Russian fossil is longer than wide, 

 as described and figured by M.M. Verneuil and Kutorga 

 ( Ge. lius., Vol. II., p. 147, PL vi., figs. 6, a, b) ; in this par- 

 ticular our shell has a closer affinity to the true lineatus, 

 which is usually transverse.* It has no sinus, and very sel- 

 dom a depressed line along the middle of one or both valves. 

 It is much smaller than the other varieties, and very closely 

 resembles the Russian fossils of this species. 



This is by far the most abundant fossil of the Coal Meas- 

 ures of the Mississippi Valley. 



Variety, striato-lineatus. 



This fossil is usually larger than the true lineatus / it is 

 generally transverse, but sometimes elongated and very gib- 

 bous. Its surface is ornamented with numerous imbricating 



f * The description of M. De Koninck, " cette coquille est ordinairement 

 d'une forme arondie et globuleuse, quelquefois transverse et elliptique," is more 

 than counterbalanced by Sowerby, McCoy, Phillips, aw others. And 

 besides, nearly all the specimens are transverse which I have observed, 

 whether from collections made in this country or in Europe. 



