PROFESSOR OWEN ON INDIAN CETACEA. ng 
“elongate, about + the length”?; but the definition of the term of comparison being 
omitted, whether it may be “length of the dental series,” “ of the mandibular ramus,” 
or “of the entire skull,” detracts from my means of testing this osteological character, 
whatever may be its value in regard to the variation in length of the “symphysis man- 
dibule”’ of the restricted Delphini of Cuvier’s system. 
In the skull, no. 423, of the “ Gadamu’” (Pl. IV.), the symphysis mandibule (figs. 
3 & 4,5,5) is more than }th the length of the entire dental series, and about {th the 
length of the entire ramus. 
Assuming, howeyer, the section or subgenus of the present Dolphin to be Steno, it 
then belongs to that subsection which is characterized as having the “ ** Beak sepa- 
rated from the forehead by a cross groove”. 
In this section the present species differs from the Delphinus (Steno) malayanus in 
colour, in number of teeth, and perhaps also in size. The D. malayanus is “ greyish 
above and below;” the dental formula — 36144, From the Delphinus (Steno) 
6—36 
frontatus of the Indian Ocean, with teeth 3—5=86 or aaa 84, D. gadamu differs 
in the greater number of teeth. From Delphinus (Steno) compressus the present species 
differs in the minor compression of the head, the shorter and less attenuated snout. 
The D. (Steno) attenuatus, Gray, departs still further from D. gadamu in the length 
40 —40 
and slenderness of the snout and the more numerous teeth, the formula mu == 
= 160, 
In the skull of D. (Steno) gadamu (P1. IV.) the maxillo-premaxillary ae of the rostrum 
is broader and lower than in D. (Steno) frontatus, the premaxillaries rise above the max- 
illaries, at the middle of the rostrum, with a more abrupt transverse convexity, and the 
maxillaries slope therefrom outward and less steeply downward to the alveolar border. 
Behind the dental series the bony palate, there formed by the back part of the maxil- 
laries, by the palatines, and pterygoids, forms a longitudinal bar convex across and 
increasing in depth as it recedes; the sides of the bar are continued into channels of 
the same length, concave transversely, and impressing the sides of the posterior palatal 
surface of the maxillaries. This undulating disposition of the bony palate subsides 
opposite the penultimate or antepenultimate teeth, in advance of which the bony palate 
is nearly flat, with a strip, 2 inches long, of the vomer at the mid line, and in advance 
of this is slightly hollow transversely, or canaliculate. 
The sockets of the teeth are in contact, about 4 lines in diameter. In the skull 
transmitted, and here noticed and figured (Pl. IV.), I count 23—23 in the upper 
jaw, and 27—28 in the lower jaw. The teeth have a long and large rounded base and 
a short enamelled crown, slightly incurved, not very sharply pointed; about ten anterior 
alveoli are coextensive with the symphysis. 
* Zoology of the Voyage of H.M.S. Erebus and Terror: “Cetacea.’ 4to. 1844, p. 43. Not any of the 
figures of the skulls of Steno, Gray, illustrate the symphysial character in question. In a specimen of Steno 
frontatus in the British Museum the mandibular symphysis is about one-fourth of the entire length of the 
skull. ? Thid. 
D2 
