DE. A. GtJNTHEE ON GIGANTIC LAND-TOETOISES. 
259 
Paet II.— DESCEIPTION OF THE GALAPAGOS TOETOISES. 
General Characters. 
Tortoises inhabiting the Galapagos archipelago may be recognized and distinguished, 
more especially from the living Mascarene Tortoises, by the following characters : — 
The nuchal plate is constantly absent. 
The posterior margins of the two gular plates are convergent, meeting at a more or 
less obtuse angle, never forming a straight, or nearly straight, transverse line. 
Neck and legs long. 
The shell is black. 
One of the scutes on the inner side of the elbow is conspicuous for its size, much 
larger than those surrounding it. 
In the skull the crown is flat ; the palate moderately concave ; the front part of the 
intermaxillary truncated, elevated. 
The symphyseal bridge between the foramina obturatoria of the pelvis is flat, broader 
than deep. 
Osseous carapace very thin. Nuchal vertebrae and limb-bones elongate. 
Among the carapaces which have formed a part of the material for this memoir, I 
can distinguish five forms; of the first four severally two are more nearly related to 
each other than to the other pair, the fifth being intermediate between these two pairs. 
In the first pair the shell is of a broader form, with more or less corrugated plates; 
in the second it is elongate and perfectly smooth. 
a. In one species of the first pair the shell is depressed, with the upper anterior profile 
subhorizontal in the male, and with the striae of the plates not deeply sculptured ; the 
sternum is truncated behind (Plate 33. fig. A) : Testudo elephant opus, 
(3. In the other species the shell is considerably higher, with declivous anterior profile 
in the male, and with the striae of the plates much more deeply sculptured ; the sternum 
has a triangular excision behind (Plate 33. fig. B, and Plate 35. fig. C.) : Testudo nigrita. 
y. In one species of the second pair the shell shows some traces of former concentric 
striae, is compressed into the form of a “Spanish saddle” in front in the male; the 
sternum is truncated behind (Plate 34 and Plate 35. fig. B) : Testudo ephippium. 
In the other species the shell is perfectly smooth, with declivous anterior profile in 
the male, and with truncated posterior extremity of the sternum (Plate 36) : Testudo 
microphyes. 
e. In the last species the shell is depressed, as in the first, with the upper anterior 
profile subhorizontal in the male, and with the lateral anterior margins reverted so as 
to approach the peculiar shape of T. ephippium ; the striae are distinct and broad ; 
sternum of peculiar shape, much constricted and produced in front, and expanded and 
excised behind (Plate 35. fig. A) : Testudo vicina. 
The degree of distinctness and affinity which obtains in the carapaces is expressed 
