46 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 37. 



tooth to the ends of the anterior and posterior cutting edges respec- 

 tively is close to a right angle; in E. heinrichii the angle measures 

 about 75°. The height of the teeth of E. heiiirichii is six-tenths the 

 length of the base, while in E. cremdatus it is seven-tenths. Never- 

 theless, the teeth of E. heinrichii appear more acute than those of 

 E. creniddtus because of the concavity of the cutting borders, those 

 of the latter species being nearly straight. The last tooth of 

 E. heinrichii seems to be less elevated than the others. Judging 

 from the apical angle and the straight cutting edges of the tooth, it 

 is believed that Newberry's figure 2b " represents a specimen of 

 E. crenulahis. 



It has been mentioned that there is in the specimen here described a 

 narrow groove that runs forward from the first tooth, becoming 

 broader at the end of the shaft. Immediateh^ in front of this first 

 tooth there is a rough surface just like that found bordering the 

 enamel of each of the teeth. These facts suggest that some of the 

 anterior and earliest formed teeth are now missing, that long before 

 the animal died some teeth had dropped off. ' Certainly it is not prob- 

 able that the animal became adult before it developed any teeth. 

 There must have been a series of teeth from very small ones up to the 

 first tooth now present. Nevertheless the writer does not believe that 

 the shaft ever extended any considerable distance, if at all, in front of 

 Avhat is now its anterior end. No doubt the trough-like processes or 

 sheaths of these earliest teeth, like those of the ones present, shortened 

 rapidly toward the front, so that they probably never extended 

 beyond the shaft as we now have it. Dr. Charles R. Eastman ^ has 

 figured a series of three teeth which diminish rapidly in size, and in 

 which the sheath of the smallest does not reach beyond the succeeding 

 one.'' Doubtless still smaller teeth occupied the space in front of the 

 smallest one present. The significance then of the groove found in 

 front of the first tooth of the type of E. crenulatiis is found in the 

 existence there, in the eacj,^' youth of the animal, of a series of small 

 teeth that were shed perhaps earl}' in life. 



Newberry '^ appears to have regarded the separate segment repre- 

 sented by his fig. 2«, pi. 5, as that of a young animal. Its sheath is, 

 however, too long for this. It nnist have been one of the later teeth. 

 It seems possible that on sufficient maceration all the teeth, with their 



« Ann. N. Y. Acad., vol. 4, pi. 5 ; Pal. Fishes N. A., pi. 39. 



» Bull. Mus. Couip. Zool., vol. 39, p. 76, fig. 7. 



'^ In case the reduction of Eastman's figure is really one-half, it seems possible 

 that his specimen belongs to an uudescribed species. Otherwise great variation 

 in size of teeth in E. heinrichii is indicated. The length of the anterior teeth 

 of the type is only about 30 mm., whereas the largest tooth figured by Eastman 

 has a length of 37 mm. 



•^Ann. N. Y. Acad., vol. 4, p. 122. 



