64 THE DOGS SICUEL. 
18. The optic foramina open into the cranial 
cavity by a single aperture in Otaria and in Steno- 
rhynchus, but not in the Phocide generally, as in 
Trichechus. 
19. The palate always extends backwards, much 
behind the last molars; but is not commonly nar- 
rowed, behind, save-in -O7a7za. - ‘It is not at) allese 
narrowed in 7vichechus. 
20. Defects of ossification commonly occur in 
the occipital in the Phoczde, but not in Ofarza and 
Trichechus. 
21. A preorbital process exists in Ofarza and 
Trichechus ; sometimes, but rarely, in the Phocide. 
22. The angle of the mandible is inflected (as in 
Marsupials) in O¢arza, but not in the other genera.” 
THE CRANIAL AND DENTAL CHARACTERS 
OF THE DIFFERENT BREEDS OF DOGS. 
The tables 1 and ii detail.a series of measurements, 
made on the skulls of a number of different 
breeds of dogs. In table 1 the maximum and 
minimum measurement of each breed is given, 
the difference between these two, and the 
average. It will be seen that the averages in 
the different breeds differ very little from one 
another; this is perhaps more noticeable, in 
tableit, im the teeth: In table the Jensen 
and breadth are compared. 
