42 
BULLETIN OF THE LABORATORIES 
pean authors, with S. ciispidatus. The wide range of variation and 
distribution make this an exceedingly valuable species for approxi- 
mately synchronizing widely distant horizons, for its vertical range is 
not extraordinary. The subjoined table of measurements and data 
will serve our present purpose in connection with the figures. In the 
view here indicated Prof. Winchell does not concur, as may be gath- 
ered from the extract from a private letter of Jan. 9th, 1888, from 
which I take the liberty to quote. 
“ I have heretofore identified with this species some specimens 
from Newark, Ohio, embracing both ventral and dorsal valves. I re- 
ceived some time since, from Prof. Hicks, specimens from Granville, 
labeled N. Carter!^ among which is a ventral valve resembling forms 
identified by me with Syringothvris typus ; but his dorsal valves differ 
from those of S. typus in having the hinge extremities prolonged and 
pointed; in more rigid costae and lack of situation in the middle of the 
anterior margin. They also lack the deep concentric wrinkles of the 
dorsal valve of S. typus. I hence separate these dorsal valves from 
Granville from S. typus ^ and leave them to represent S. Carteri^' 
Fig. 17, of Plate II, serves to illustrate the usual form of the 
smaller and more finely striate form called S. carteri, though these 
often have acuminate angles d'he difference between such forms and 
those figured 4-6 Plate V, is completely bridged, nor does it seem 
possible to exclude the extreme variety drawn in Fig. 7, Plate I. 
The species reaches its maximum in the congl. II, but is charac- 
teristic of our middle division, beyond which it extends somewhat 
both above and below. 
Spirifers of the S. inarionensis group. 
This is the most perplexing subdivision of the genus. Four nom- 
inal species- contend for admission and present characters so concor- 
dant as almost to baffle discrimination. These species are N. striati- 
formis. Meek, S. cenU^onata, Win., N. biplkatu-s, Hall, and S. marion- 
ensis, Shumard. All of these have been at some time identified in 
Ohio. S. striatiformis alone presents such peculiarities as make it 
easily identified when perfectly preserved. The S. biplicatus described 
by Meek in the Ohio Palaeontology is stated by Winchell to be his S. 
centronata, thus eliminating a second from the set. The following 
