No. 1605. ON THREE SPECIES OF SEA-TURTLES—HAY. 191 
farther from the snout in the loggerhead than in the other turtle. 
The pedicels of the quadrates of the loggerhead are swung back- 
ward from 15 to 25 mm. farther than in the bastard-turtle. One 
result of this is to bring the occipital condyle of the loggerhead on 
a line with the hinder faces of the pedicels in the loggerhead, while 
in the bastard-turtle it projects considerably behind the pedicels. 
- Another result is to make the upper anterior end of the quadrate, 
at its union with the prootic (Plate VIII, fig. 1), project much farther 
in front of the pedicels in the loggerhead than they do in the bas- 
tard-turtle (Plate VIII, fig. 2). This advanced position of the 
quadrate and prodtic appears to become accentuated with age in 
the loggerhead. 
The greater breadth of the maxille of the bastard-turtle below the 
orbit 1s to be noted. 
The measurements show that the posterior nares of the loggerhead 
are much narrower than in the bastard-turtle. The pterygoids of the 
two species differ greatly. Where the palate is most constricted the 
pterygoids of the bastard-turtle (Plate VIU, fig. 2) are much nar- 
rower than in the loggerhead (Plate VIII, fig. 1), while in front they 
broaden greatly. Moreover, in the loggerhead there are only ves- 
tigial ectopterygoid processes. while in the bastard-turtle these are 
strongly developed. 
As might be expected from the backward position of the pedicels 
of the quadrates, the rami of the lower jaw of the loggerhead (Plate 
XI, fig. 3) are considerably longer than those of the bastard-turtle 
(Plate XI, fig. 4); the coronoid processes are likewise thrown 
farther backward. ‘The rami are less arcuate, and thinner. On the 
other hand, the mental foramina he considerably nearer the tip of the 
jaw. 
Returning to the upper surface of the skull, we find that the frontal 
bones of the bastard-turtle (Plate VII, fig. 2) enter the rim of the 
orbit for a short distance, while in the loggerhead (Plate VII, 
fig. 1) they are normally widely excluded therefrom. Boulenger has 
noted the fact that occasionally in the loggerhead the frontal on one 
side or the other enters the rim of the orbit. Doubtless it will be 
found that sometimes the frontals of the bastard-turtle are excluded 
from the orbit; but such variations hardly affect the specific value of 
the character. | 
The roof of the mouth of the bastard-turtle (Plate VITI, fig. 2) pre- 
sents on each side a prominent, rounded, bony ridge, which runs along 
the suture between the maxilla and the palatine. This ridge supports 
the ridge of the horny alveolar surface which has been described 
above. Only occasionally and in the smaller individuals of the log- 
gerhead is there seen any trace of a similar ridge. Masticatory ridges 
“Proc, Zool. Soc, Lond., 1890, p. 618, 
