210 Field Columbian Museum — Geology, Vol. i. 



were obtained. Some of the specimens although entirely opaque in 

 the outer whorls were very translucent in the inner whorls so that the 

 suture lines were easily discernible. 



Fig. i, PI. XXIII, represents a number of sutures as follows: a. 

 The first suture is angustisellate and represents the ananepionic stage. 

 b. The second suture is a transition from the suture of Anarcestes 

 to that of Tornoceras. c. The third suture is Tornoceras. d. The 

 fourth suture is a transition from Tornoceras to Glyphioceras, or 

 possibly Prionoceras. e. The fifth suture is Glyphioceras. /. Is 

 Glyphioceras. g. Is a suture on the second whorl which is Gastri- 

 oceras but is just approaching Paralegoceras. //. Is a suture on the 

 third whorl, diameter 5mm., and is the ammonitic radical, probably 

 nearest Pronorites. 



The suture on the first part of the fourth whorl has much the ap- 

 pearance of the suture of 6". warreni, and toward the end of that 

 whorl reaches the adult form. 



In Figs. 2, 3 and 4, PI. XXIII, views of the protoconch are given 

 which represent the phylembryonic stage of the type Scaphites 

 nodosus Meek. 



Figs. 7-12, PI. XXIII, represent six stages of growth between 

 the close of the brephic and the beginning of the ephebic stage. 



Fig. 5, PI. XXIII, shows the suture of the adult form of S. 

 warreni, and Fig. 6 that of 6". nodosus, Museum specimen No. 3653, 

 University of Chicago. 



SCAPHITES WARRENI— Meek. 



Proc. Acai>. Nat. Sci. of Phila., p. 185. i860. 



(PI. XXII, Fig. 1 and PI. XXIII, Fig. 5. Mus. No. P 5940.) 



Revised and Enlarged Description. " Shell medium size, trans- 

 versely subovate, moderately compressed, inner volutions nearly cir- 

 cular, closely involute, and composing a little more than one-half the 

 bulk; deflected body portion longer than the diameter of the involute 

 portion and rather more proportionally than the inner turns; surface 

 costate and without proper nodes; costae small on the inner whorls, 

 where they do not differ materially in size, but on the body part 

 some, usually every third or fourth one, become more prominent 

 than the others, and extend entirely across from the inner side to 

 and over the periphery, in passing upon which they bifurcate, or give 

 off branches and assume, with these, a uniform size. The aperture 



