J. B. Hatcher — Recent and Fossil Tapirs. 177 



Systemodon through the intermediate forms Isectolophus (Hel- 

 aletes) latidens of the Bridger, Isectolophus annectens from the 

 Uinta, Protapirus simplex and P. oliquidens from the White 

 Kiver and perhaps Tapiravus from the Loup Fork. They cite 

 as evidences against this line of descent, the union of the pro- 

 toloph with the parastyle instead of the paracone in both species 

 of Isectolophus and the submolariform character of sup. pms. 3 

 and 4 in that genus as described by Osborn.* I have carefully 

 examined both of these types and can say that the union of the 

 protoloph is with the paracone rather than the parastyle, the 

 real union being with the ectoloph a little in front of the para- 

 cone. In regard to the sup. pms. Prof. Osborn says (on page 

 519 of the paper just cited) : u These are wanting in the Uinta 

 specimens, but the Bridger species which was formerly referred 

 by us to Helaletes (H. latidens) is closely related to Isectolo- 

 phus, if not generically the same, and shows double internal 

 lobes upon both pm. 3 and pm. 4;" and just below on the 

 same page in his Generic characters he says, " Fourth and 

 probably third premolars in both jaws submolariform or with 

 double internal cones." These are certainly errors of observa- 

 tion and description, since in sup. pm. 4, which is the only 

 superior premolar complete and in position in the type of 

 II. latidens, the internal cone is absolutely simple and without 

 the faintest signs of division, the same may be said of the 

 only sup. pm. at present known of Isectolophus annectens. 

 Prof. Osborn further states on page 521 that the first inferior 

 premolar abuts against the canine; and on page 519, that 

 there is no diastema behind the canine, these are characters not 

 shown in any of the type specimens of the genus ; and if we 

 stop to consider the characters which obtain in this region of 

 the skull in the White River Tapiroids, together with the 

 extreme conservativeness of this entire group in accomplishing 

 any dental or other changes, we may infer that it is quite prob- 

 able, that in the Uinta Tapiroids, there was a considerable post- 

 canine diastema, with a marked constriction of the symphysis 

 of the lower jaw, otherwise we shall have to conclude that the 

 Tapirs, toward the close of the Uinta, began to progress very 

 rapidly, and in the interim between that and the beginning of 

 White River times they outstripped all other Perissodactyls in 

 accomplishing anatomical changes, a very improbable assump- 

 tion. 



After studying carefully all the material referable to Isecto- 

 lophus annectens I can only substantiate the views of Scott, 

 Osborn, Wortman and Earle in referring Isectolophtis to the 

 Tapiridce. I do not consider Isectolophus {Helaletes) latidens 

 from the Bridger as belonging to the genus Isectolophus. 



* The Mam. of the Uinta Form. Trans. Am. Phil. Soc., 1889, pp. 461-572. 



Am. Jour. Sci.— Fourth Series, Vol. I, No 3 —March, 1896. 

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