314 Proceedings of Royal Society of Edinburgh. [sess. 
with the mid-palatal suture, and their posterior borders formed 
a continuous transverse edge. The hyoid apparatus consisted of the 
customary elements. The teeth were conical and pointed, small in 
size, and the longest projected only 8 mm. beyond the gum; 
the six most anterior teeth in the upper jaw and the three most 
anterior teeth in the mandible had not cut the gum. The dental 
formula was §y. The mucous membrane covering the hard 
palate was perfectly smooth. The tongue was free at the tip. 
The anterior nares were not symmetrical, the right being larger 
than the left ; the mes-ethmoid was prolonged into the medio- 
Fig. 3. — Dorsal view of the skull of Delphinus acutus. 
rostral cartilage. The tympanic bullae were bilobed ; the outer 
was the larger of the two lobes and smooth. The bulla was 
32 mm. long and 19 mm. in greatest breadth. The petrous bone 
was 31 mm. long and 19 mm. broad.* 
Systematic writers on the Cetacea have attached importance in 
the discrimination of the species of Dolphins to the relation 
between the length of the skull, measured in a straight line, from 
the occipital condyl to the tip of the beak, and the length of the 
beak itself. I have accordingly, for purposes of comparison, taken 
* See my paper on the ‘‘Sperm Whale,” in Proc. Roy. Soc. Edin., vol. 
xxiv. p. 430, 1903, for measurements and characters of the tympanic and 
petrous bones in the Cetacea. 
