XIII. STRUCTURE OF THE FORE LIMB AND MANUS OF 

 BRONTOS.AURUS. 



By J. B. Hatcher. 



Notwithstanding the abundance of the remains of the Sauropod 

 Dinosaurs in the Jurassic deposits of the West and the exceptional 

 vigor with which the collecting of these remains has been carried on, 

 in the earlier days by the late Professors Marsh and Cope and more 

 recently by Osborn, Williston, and the Carnegie and Field Columbian 

 Museums, much still remains to be learned concerning the complete 

 osteology of even the commoner genera and species. By the com- 

 bined efforts of all engaged in the collecting and studying of Dinosaur 

 remains, rapid and substantial progress is being made in our knowl- 

 edge of the structure of these gigantic reptiles which in size equalled 

 or surpassed that of any other known animals either living or extinct. 

 The facts set forth in the present paper concerning the structure of 

 the manus of Brontosaurus, which most likely does not differ materi- 

 ally from that of the same element in the other genera of the Sauro- 

 poda, affords a striking illustration of the proximity with which one 

 discovery follows another, shedding new light on doubtful points and 

 making it for the first time possible to substitute facts for conjecture 

 concerning the structure of previously unknown characters. Hardly 

 had the Memoir on Diplodocus,^ prepared by the present author and 

 based upon much the best material pertaining to that genus yet dis- 

 covered, been received from the press, than a second skeleton, be- 

 longing to a distinct but closely allied genus, Bi-ontosauriis, was re- 

 ceived at the Museum. This contained, beside many other parts of 

 the skeleton, a nearly complete fore limb and foot, elements entirely 

 wanting in our skeleton of Diplodocus. This fortunate discovery 

 calls for an entire revision of the structure of the manus of Brontosaurus 

 at least, as that element has been reconstructed, figured and described 

 in recent publications by Prof. FI. F. Osborn," Avhile at the same 

 time making it extremely probable that the manus of both Morosaurus 



' Memoirs of the Carnegie Museum, Vol. I., No. I. 



^Bull. Am. Mus. Nat. Hist., Vol. XII., pp. 161-172, and Vol. XIV., pp. 199-208. 



356 



