ON RHAMPHORHYNCHUS BUCKLANDI 147 
these discrepancies, however, as on another fact, viz., that I cannot 
discover the least trace of any alveolus behind the fifth, in either 
ramus of the Sarsden species, although on the right side more than 
an inch of the ramus is preserved behind the fifth dental socket, 
and although on the left side the ramus is so broken away that any 
remains of a tooth, or of the alveolus in which it was lodged, could 
hardly fail to be visible. 
If the differences which I have indicated should prove to be 
constant, I would propose for Lord Ducie’s fossil the name of 
Rhamphorhynchus depresstrostrts. 
The ramus in the Society’s Collection also differs more than I 
at first imagined from that belonging to Professor Quekett. The 
distance from the anterior margin of the articular cavity to the 
posterior margin of the hindmost alveolus is, in the latter, to the 
like measurement in the former, as 13 to 23. The distance of the 
“pit” from the anterior margin of the articular cavity and from 
the last alveolus, in the two cases, is in about the same proportion ; 
but the depth of the jaw is not in the same ratio, nor is the space 
occupied by the three corresponding alveoli; and in the Society’s 
specimen the highest part of the coronary region is far more for- 
ward than in the other. If, however, we are to be guided by the 
proportions first stated, the mandible in question must have been 
between nine and ten inches long, and the differences observed 
might be accounted for by the different ages of the animals whence 
the parts compared were derived. As I am not aware of any 
evidence tending to show the nature of the variations undergone 
by the mandibles of the Péerosauria in their progress from youth 
to age, I must leave open the question of the specific identity of 
Professor Quekett’s specimen with that in the museum of the 
Geological Society. 
It will be understood that I regard the former as the typical 
Stonesfield Pterosaurian; and I now proceed to compare it with 
the known remains of other Rhaniphorhyneht. 
To the four species referred to Rhamphorhynchus by Von Meyer, 
viz. macronyx, Muenstert, Gemmingi, and longicaudus, Professor A. 
Wagner, in a recent very valuable memoir,! adds longémanus, curtt- 
manus, hirundinaceus, crassirostris, and Banthensis, making nine 
species in all. Wagner considerably adds to and amends the def- 
nition of Rhamphorhynchus given by Von Meyer. Thus, while in 
the Péerodactyli proper the cranium exhibits on each side only two 
1 Neue Beitrage zur Kenntniss der urweltlichen Fauna des lithograpbischen Schiefers. 
Erste Abhandlung; Saurier. Abhand. d. Konig. Bayerischen Akademie, viii. (1858.) 
L 2 
