44 
THE EACES OP THE MASCAEENES, 
Skull. — There are altogether thirteen skulls in a more or less fragmentary condition, 
and five mandibles, in the collections of the British and Cambridge Museums. They 
can be referred to two species — the first having three serrated dental ridges along the 
lower jaw (Testudo triserrata), the second having only two ridges [Testiido inepta). 
a. Testudo triserrata (Plate XXIII. fig. A). — 1. Frontal region perfiectly flat, broad, 
its greatest width being a little more than one half of the distance of the tympanic 
condyles. 2. Only the anterior half of the parietal forms a flat surface, the posterior 
being compressed into a trenchant crest passing into the very long occipital spine. 3. 
The tympanic case with the mastoid is produced backwards, so that the paroccipital 
margin appears as a deep semicircular excision. 4. The impression on the lower surface 
of the occipital in front of the condyle is very shallow. 5. On the front margin of the 
temporal fossa, corresponding to the suture between parietal and tympanic, immediately 
in front of the foramen carotidis externse, there is a very large and projecting flat 
condyle-like tuberosity for the insertion of a portion of the temporal muscle. 6. Tym- 
panic cavity large, with a nearly circular outer tympanic rim, which is posteriorly 
interrupted by the notch for the Eustachian tube. 7. This notch is not very remote 
from the columellar foramen, which is on an elevated ridge crossing transversely the 
tympanic cavity. 9. The front margin of the intermaxillaries projects but slightly 
beyond that of the frontals ; so that the plane of the nasal opening is nearly perpen- 
dicular and as broad as high. 10. The inner nostrils are advanced, not very distant 
from the end of the snout, and, on the palatal view of the skull, hidden for the 
greater part below the alveolar lamella of the maxillaries. 11. The intermaxillaries 
are short, about one third the length of the maxillaries ; their foremost portion is 
deeply hollowed out below, and vertically bent downwards to form the beak. The 
suture between the intermaxillary and vomer is immediately behind the inner angle of 
the alveolar edges of the maxillaries. The alveolar maxillary surface is provided with 
three denticulated ridges, the inner of which runs parallel to, but at a distance from, 
the inner alveolar edge. 12. The palatal region is much less concave than in the Aldabra 
Tortoises, and without median longitudinal crest. 13. Anterior surface of the tym- 
panic pedicle deeply excavated. 14. Lower jaw with a triple serrated alveolar ridge, 
the two inner ridges being rather close together and belonging to the same raised 
osseous tract. 
b. Testudo inepta (Plate XXIII. fig. B). — The skull of this species is so similar to 
that of Testudo triserrata that only the following important points in which it differs 
need be mentioned. 11. The alveolar surface of the maxillary shows three denticulated 
ridges, one being confluent with the outer, and one with the inner alveolar margin. 
14. Lower jaw with two serrated ridges only. 
To judge from the skulls, both these species must have had smaller heads than the 
Galapagos Tortoises, The largest of our series of skulls belong to Testudo triserrata, 
one of them being 50 lines long (to the end of the occipital condyle) and 38 lines broad 
