DE. A. G-UNTHEE ON GIGANTIC LAND-TOETOISES. 
263 
Osteology. — In the preceding remarks, as well as in the following notes on the osteo- 
logical characters of the various species, it is not my intention to give such a complete 
description as would include every detail common to all the species of Testudo ; but I 
shall limit myself to those points only by which the various species of gigantic Tortoises 
differ from one another in a marked manner. 
The skull, then, of our adult example of Testudo elegghantopus (specimen No. 1, fig. A 
of Plates 37—39) is distinguished by a very short snout and a singularly raised occipital 
crest; it is 4-f inches long, measured from the front margin of the intermaxillary to the 
occipital condyle, and 4 inches broad in its widest part, between the zygomatic arches. 
1*. The frontal region is perfectly flat, broad, passing into the very short snout, its 
greatest width (in front of the postfrontals) being as much as one half of the distance 
between the tympanic condyles. 2. The occipital crest is enormously developed; it 
rises abruptly above the level of the skull, is strongly compressed and scarcely attenuated 
behind, its extremity being broad and rounded. 3. The tympanic case, with the mastoid, 
is produced backwards, the hind margin of the paroccipital forming a rather strong 
curve (fig. A, a). 4. A deep hollow on the lower surface of the occipital in front of 
the condyle (Plate 39. fig. A, b). 5. On the front margin of the temporal fossa, corre- 
sponding to the suture between parietal and tympanic, and immediately in front of the 
foramen carotidis externae , there is a large, prominent, concave rough tuberosity for the 
insertion of a portion of the temporal muscle (Plate 37. fig. A, c); a broad and deep 
groove ( d ) separates this tuberosity from the zygomatic arch. 6 r j\ Tympanic cavity 
large, but constricted by the groove just described; the outer tympanic rim is subcir- 
cular, with a broad and deep notch (e) in the posterior part of its circumference for the 
passage of the Eustachian tube. 7. The columella is attached to, and rests upon, a long, 
straight, sharp ridge, which runs from the notch mentioned to the stapedial foramen. 
8. The posterior wall of the inner tympanic cavity, which, in fresh examples, is formed 
by cartilage, and an open space in the preserved skull after maceration, is but limited 
in extent, about one seventh of the area of the tympanic opening. 9. The front margin 
of the intermaxillary projects beyond that of the frontal, but much less than in the 
Mascarene Tortoise, so that the nasal opening, although still obliquely sloping down- 
wards, is as high as broad. 10. The position of the choanse is advanced forwards ; yet, 
on the palatal view of the skull, a portion of them may be seen uncovered by the alve- 
olar lamellae of the maxillaries (Plate 39. fig. A). 11. The intermaxillaries are short, 
* In this and the following descriptions of the skulls the same points are noticed under the same numbers, 
a plan by which the comparison of the several parts (sometimes described many pages apart) is much facilitated. 
The significance of certain modifications of structure noticed here will become more apparent when we shall 
treat of the skulls of'the Mascarene Tortoises. 
i It is very singular that although the osseous parts of the auditory organ are so well developed, nevertheless, 
according to the unanimous testimony of the observers, these Tortoises are absolutely deaf. I find this con- 
firmed so far in my young living example that it never takes notice of the noisy approach of a person whom it 
cannot see, nor is it disturbed by the fall of a stone behind its back. Perhaps the faculty of hearing, although 
never acute, is not entirely lost until the individuals have attained to a great age. 
2 hr 2 
