1898-1902. No. 32.] FOSSIL FAUNAS FROM SERIES B. 27 



land. The specimens differ, however, by having a relatively distinct 

 concentric striation, while the other form has a very faint surface-orna- 

 mentation, viz. only a few, very slightly marked lines of growth. The 

 concentric lines in the Arctic form are very closely arranged, and in 

 their anterior part exhibit distinct fimbriate spines. 



On grinding a ventral valve, I observed two strong, diverging dental 

 plates but no median septum. These characters distinguish the form from 

 the younger Reticularias and Squamularias, which embrace species ex- 

 ternally very much like ours. According to Dr. G. GIRTY, who in his 

 extensive paper on the Carboniferous of Colorado (Professsional Paper 

 U. S. G. S., vol. 16, ps. 387 392) discusses the genera in question with 

 considerable fullness, Reticularia has a medium septum and dental plates, 

 whilst Squamularia has neither. 



Occurrence: B, lower part, Reindeer Valley. 



Spirifer vanuxemi HALL, var. prognostica SCHUCHERT. 

 PI. VIII,, fig. 4. 



1913. Spirifer varuxemi HALL, var. prognostica SCHUCHERT. Geol. 

 Survey of Maryland, Low. Devonian, p. 403, pi. 68, figs. 3435, 

 pi. 69, figs. 13. 



This little form, that is very characteristic of the Keyser member 

 of the Lower Helderberg in Maryland, is represented in the material by 

 a fair number of specimens, some of which are fairly well preserved. 

 The identification has been made with certainly, as I have had the 

 opportunity of seeing typical Maryland-specimens in Professor SCHUCHERT'S 

 collection in New Haven. The size varies somewhat, the largest speci- 

 men measured having a length of 7 mm., and width of 9 mm. Where 

 the surface is well preserved a concentric striation, the lines marked 

 by minute fimbriae can be seen. 



The American variety is exeedingly near to Spirifer vanuxemi HALL 

 from the Manlius of New York and New Jersey, the only distinguishing 

 character being somewhat more numerous plications in the variety. 



Several small specimens from the lower part of Series B, from the 

 Valley south of Borgen, measuring only about 7 mm. in width, 6V2 in length, 

 as far as can be seen from the not very well preserved exterior has only 

 about 3 plications on each side of fold and sinus, and might therefore 

 perhaps be determined as S. vanuxemi. 



Occurrence: B, lower part, Reindeer Valley. B, upper part, in the 

 fragment-limestone, Valley south of Borgen. 



