116 MEMOIRS OF THE CARNEGIE MUSEUM 
tion of this problem, although from Knight’s evidence and the close resemblance of 
this paddle to the fore limbs known, I am inclined to believe that Marsh was 
wrong and that the limb figured and described by him as pelvic is really a pectoral 
extremity. It will be noticed by an examination of Marsh’s drawing (see fig. 25) 
that there is no contact between the proximal and distal portions of the femur (?) 
which renders it somewhat more difficult to make accurate comparisons. 
The additional finger developed in Baptunodon and the fact that some of the 
Ichthyosaurs have as many as ten, is explained by Dr. 8. W. Williston as follows :* 
“The additional fingers of the Ichthyosaurs may be also explained in a similar way. 
The margin of the flipper has become hardened by fibro-cartilage, which by the 
movement of the fingers was broken into segments, each of which finally took on 
ossification. A division of the phalanges by segmentation would certainly have to 
take place immediately in order to preserve the integrity of the paddle as an organ 
of propulsion. If this explanation be correct, then the additional ossification in the 
fore arm in the present form, as well as in the carpus, are not displaced elements but 
new ones without homologies.” 
Discussion OF THE GENUS BAPTANODON. 
In the year 1879 Professor O. C. Marsh proposed and established the genus 
Sawranodon * which being preoccupied was later replaced by the name Baptanodon.” 
Since that time all Ichthyosaurian remains from the American Jurassic have been 
referred to that genus. In his original description Marsh distinguishes Sawranodon 
natans (the type species of the genus) from Ichthyosaurus by the absence of teeth, 
of which he says: “The jaws appear entirely edentulous and destitute even of a 
dentary groove.” ‘This statement is corroborated in a second paper * in the following 
lines: ‘Since the first species of the present genus was described by the writer, eight 
other specimens of the same group have been discovered and are now in the Yale 
Museum. In three of these the skull is preserved, but there are still no indications 
of teeth, so that we may consider these reptiles as entirely edentulous.” 
_ While cleaning the skull pertaining to specimen No. 603 preparatory to study 
the discovery was made that the animal had teeth,” two of which were found 
45 Williston, S. W., ‘‘ North Amer. Plesiosaurs,’’ Part I., Field Columbian Museum, Pub. 73, Geol. Series, Vol. II., 
No. 1, 1903, p. 70. 
4° Marsh, O. C., ‘‘ A New Order of Extinct Reptiles (Sauranodonta) from the Jurassic Formation of the Rocky 
Mountains,”’ Am. Jour. of Sci. (3), Vol. XVII. 
“7 Marsh, O. C., “ Note on Sauranodon,’’ Amer. Jour. of Sci. (3), Vol. XIX., 1880. 
*© Marsh, O. C., ‘‘ Limbs of Sauranodon, with Notice of a New Species,’? Amer. Jour. of Sci. (3), Vol. XIX. 
Feb., 1880. 
“Gilmore, C. W., ‘‘ Discovery of Teeth in Baptanodon, an Ichthyosaurian from the Jurassic of Wyoming,”’ 
Science, N. S., Vol. XVI., Dec. 5, 1902. 
