32 Annals of the Carnegie Museum. 



The shape of the shell is not semicircular in outline, but is triangular, 

 and much like that of S. mucronatus Conrad. The cardinal margin 

 terminates in acute and not rectangular or obtuse extremities. The 

 proportions of height to width are dififerent. Spirifer pinonensis has 

 a ratio of .76 : i and a height of .92 in. and a width of 1.20 in. Six 

 specimens of Spinifer raymondi were measured and gave the following 

 dimensions: I. Height 12 mm.; width 25 mm.; ratio .48 : i. II. Height 

 15 mm.; width 30 mm.; ratio .5 : i. III. Height 11.5 mm.; width 21 

 mm. ratio, .54 : i. IV". Height 13 mm.; width 23 mm.; ratio .56 : I. 

 V. Height 14 mm.; width 24 mm.; ratio .58 : i. VI. Height 20 mm.; 

 width 30 mm.; ratio .66 : I. 



Specimens of S. pinonensis have from eleven to fourteen rounded 

 plications on each side of the mesial fold and sinus, and these plications 

 are covered with radiating striae. Spirifer raymondi has from nine 

 to twelve rounded radiating plications on each side of the mesial fold 

 and sinus, and in no specimen were more than twelve plications 

 observed. No minute striations were seen on the plications of any of 

 the specimens. All of the well-preserved specimens of 5. raymondi 

 show a slight fold in the middle of the sinus, and the surfaces of both 

 valves are marked with rather fine undulating lines of growth. 



Specimens from the Jefferson limestone near Princeton, Montana, 

 have been by Dr. Kindle, referred for comparison to Spirifer argen- 

 tarius Meek, which Dr. Schuchert believes to be the same as 5. pinon- 

 ensis Meek. The specimen figured by him is apparently identical 

 with the average specimen of Spirifer raymondi. 



Four specimens of the European species Spirifer elegans Stein, in 

 the Museum of Comparative Zoology (Schultze's Collection) show a 

 very marked resemblance to the specimens of Spirifer raymondi. The 

 points of difference are that the specimens of 5. elegans are one-third 

 to one-half larger than S. raymondi, and the delthyrium in S. elegans 

 is an equilateral triangle, while in 5. raymondi its height is to its width 

 as I : .6. The sinus in S. elegans is also somewhat broader and 

 perfectly smooth. 



On account of all of these differences from any described forms, it 

 seems advisable to place these specimens from the Three Forks 

 Formation under the new specific name Spirifer raymondi. This new 

 species is named in honor of Dr. Raymond who collected the first 

 specimens from Three Forks. The type is in the Carnegie Museum. 



Locality. — Specimens of Spirifer raymondi are numerous in the 



