NATURAL SCIENCES OF PHILADELPHIA. 257 



In form and proportions this large species seems to agree nearly with 0. 

 Munsterianum, of Koninck, from the carboniferous rocks of Vise, Tournay, but 

 it attains a greatly larger size, and also differs in having its siphon central. It 

 is probably the largest species known in our carboniferous rocks. 



Locality and position. Randolph County, Illinois. Chester division of Sub- 

 carboniferous Series. 



Orthoceras Winchellii, M. & W. 



Shell rather rapidly tapering ; section nearly circular, its greater and small- 

 er diameter being as 10b' to 100 ; septa moderately concave, not oblique, dis- 

 tant one -fifth the greater diameter of the shell at the point of measurement, 

 and showing a gentle backward curve in crossing the dorsal and ventral sides ; 

 siphon very small at the points where it passes through the septa (probably 

 swollen or beaded between), placed on the shorter axis of the septa only about 

 its own breadth from the margin. Surface nearly smooth, or with more ob- 

 scure lines of growth, which, like the margins of the septa, make a slight 

 backward curve in crossing the dorsal and ventral sides. 



Length of an entirely septate specimen, imperfect at both extremities, 3 

 inches ; greater diameter at the larger end, 1*50 inches ; apical angle 15, ap- 

 parently becoming greater towards the smaller end. 



This species seems to be somewhat similar to 0. occidentale, of Prof. Win- 

 chell, from his Marshall Group (Am. Journ. Sci. vol. xxxiii. 18t>2, 356), but 

 differs in being more rapidly tapering, and in having its siphon nearly margi- 

 nal, instead of placed midway between the centre and margin of the septa. 

 If much swollen between the septa, its siphon must be indeed quite marginal 

 at these joints. 



Named in honor of Prof. A. Winchell, State Geologist of Michigan. 



Locality and position. White Sulphur Springs, Delaware County, Ohio. 

 Hamilton Group. Devonian. 



Genus PHRAGMOCERAS, Broderip, 1834. 

 Phragmoceras Walshii, M. & W. 



Shell very large, clavato-sublunate in form, moderately arched, increasing 

 rather rapidly in size from the smaller end to near the middle, and thence ap- 

 parently somewhat tapering towards the aperture ; more or less compressed. 

 Outer or body chamber apparently rather short. Septa very oblique, (proba- 

 bly to some extent due to compression and distortion), comparatively closely 

 arranged, the chambers between scarcely equalling one-sixth the greater di- 

 ameter of the shell at the widest part, and one-eighth towards the smaller 

 end. (Siphon, surface and aperture unknown). 



Length of specimen, (imperfect at both extremities), measuring alon- the 

 middle of the side parallel to the curve, about 15 inches ; greatest breadth 

 near the middle, 5 inches; smaller do. at same place, 3-50 inches. Greater 

 breadth at smaller end, 240 inches. Of the whole length of the specimen 22 

 of the smaller chambers form 10 inches, and the remaining portion of the 

 body chamber the other five inches. 



The only specimen of this large shell we have seen is very imperfect, and 

 much distorted, so that it is qnite probable some of the characters given in 

 the above description, will require more or less correction when good speci- 

 mens can be obtained. Its large size, general form, and rather closely arranged 

 septa, however, will probably render its identification not very difficult. 



The specific name is given in honor of B. D. Walsh, the well known Ento- 

 mologist, of Rock Island, 111. 



Locality and position. Rock Island, Illinois. Hamilton division of the 

 Devonian. 



1865.] 



