DESCRIPTIONS OF SPECIES. 295 



1888. Spiriferlna solidirostris. Herrick, Sci. Lab. Denison Univ., Bull., vol. 3, p. 47, pi. 1, fig. 8 (?); 

 pi. 2, figs. 9-11; pi. 5, fig. 13. 



Waverly group: Licking County, Ohio. 

 1895. Spiriferina solidirostris. Herrick, Geol. Surv. Ohio, Rept., vol. 7, pi. 21, fig. 13. 



Burlington: Ohio. 

 1899. Spiriferina solidirostTis. Girty, V. S. Geol. Surv., Mon., vol. 32, pt. 2, p. 71, fig. 10a. 



Madison limestone: Yellowstone National Park. 

 1901. Spiriferina solidirostris. Weller, Acad. Sci. St. Louis, Trans., vol. 11, p. 198, pi. 20, figs. 2-4. 



Kinderhook: Bed 7, Burlington, Iowa. 



This species is found in the San Juan and the Canyon areas and in each it is 

 rather an abundant form. It is rather constant in the characters shown and can be 

 brieily described as follows: 



Shell of medium size, transverse. The width of a large specimen is about 20 

 mm. and the length 11 mm., but the average size is considerably less. The fold and 

 sinus are rather narrow and deep but usually show a tendency toward division. 

 Accordinglj', the fold is centrall}'^ flattened or even slightly grooved, and the sinus 

 shows a corresponding condition. The lateral plications are simple and strong. In 

 large specimens six of these are found on each side of the sinus and five on the fold, 

 but in smaller examples these numbers are dimmished by one. The area of the 

 ventral valve is high, but it is sometimes nearly flat, and at others more strongly 

 incurved. The sui'face is marked by numerous regularly disposed concentric 

 lamellffi, which become stronger and more crowded near the margin. Their 

 edges appear delicatelj' fluted, a circum.stance which can doubtless be interpreted as 

 indicating that they bore spinous firabi'iffi. The punctation is rather coarse and 

 very abundant. The ventral valve is provided with a strong median septum and also 

 with strong dental lamella?. 



This form is probably identical with part of the material from Yellowstone Park 

 which I identified in 1896 as A^;*. solidirostris. The fossils then in hand were few and 

 poor and I now suspect that more than a single species was involved. The specimen 

 figured at that time has moi'e numerous and more slender ribs than the Colorado 

 type, but some of the other specimens approach it closely. 



8pi7'iferina solidirostris f would much resemble 8p. svhelliptica at the same 

 size in general configuration and in the character of its surface ornamentation, but 

 McChesnejf's species does not show a faint median plication on fold and sinus. A 

 common form in the Waverh' group at Sciotoville, Ohio, which can probably be 

 identified with Bp. depressa Herrick, also resembles the Colorado form in general 

 appearance, but it is without a median plication, and the lamellose concentric striae 

 are considerably coarser. Another related form is Sp. suhtexta White, but the latter 

 is too little known for comparisons to be of value. It seems to-have a simple fold 

 and sinus, which should distinguish it from the Colorado form, but it must be 



