7. ORCA. 289 



the orbit (or), so defined below, is longitudinally oblong, more arched 

 above than below, 2" 2'" in fore-and-aft diameter, 1" 2'" in greatest 

 vertical diameter, the chamber communicating, of course, largely with 

 the temporal fossa (m) and the smaU antorbital fossa {d), external to 

 which is the rough malo-maxillary fossa («). 



" The squamosal consists chiefly of its articular or zygomatic part 

 (27)i which is deep in proportion to its length, truncate, and three- 

 sided; the outer side is slightly convex or rather rough, 1" 5'" deep 

 posteriorly ; the inner side is divided between the articular cavity, 

 rough for syndesmosis with the mandible, and the smoother surface 

 internal to it, which extends mesiad in a triangular depressed form 

 (27') beneath the back part of the alisphenoid (6), but without join- 

 ing it; the upper surface, of an iaequilateral shape, contributes a 

 lower wall to the temporal fossa. The squamous portion {t) con- 

 tinued upwards from this facet, is triangular, with a rounded apex, 

 about an inch in height and rather more in breadth ; it is applied 

 against the alisphenoid and parietal : the rough posterior tract (8) 

 articulatiug with the parietal (7') and exoccipital (2), and contributing 

 to the outer waU of the otocrane, I consider to be the ' mastoid,' 

 confluent with the squamosal, and forming the bone which should be 

 termed ' squamo-mastoid ' (27-8, fig. 57). The mastoid part (8) 

 terminates below in a rough, fiattened, triangular surface, 5" 7'" in 

 diameter, which is divided from the zygomatic or articular process 

 of the squamosal (27') by a deep fissure. On the inner side of the 

 base or back part of the mastoid, in the line of its suture with the 

 parietal, is the (stylomastoid ?) fossa, &c. : the squamosal forms no 

 part of the inner or proper wall of the cranial cavity. 



" The glenoid or mandibular-articular surface is longitudinally 

 oblong, 1" 5'", by 8'" in diameter, moderately concave, least so trans- 

 versely, and looking inward, downward, and with a slight inclination 

 forward. 



" The mandible (29-32, fig. 57) offers no notable peculiarity, save 

 that which relates to shortness in proportion to the entire skull, con- 

 currently with the same specific character of the upper jaw. The 

 depth of the ramus at the coracoid process is relatively as great as 

 in the longer-jawed species, and consequently bears a greater ratio 

 to the length of th* entire ramus ; this in the present skull is 7", the 

 greatest vertical extent of the ramus being 2" 6'" : the shallowest 

 part of the ramus is where it supports the teeth (32) ; it deepens a 

 little at the short symphysis. There are fourteen alveoli, approxi- 

 mated in a common groove, in each mandible, extending along 3" 3'" 

 from the symphysis. The corresponding groove of the upper jaw 

 shows seventeen alveoli, along an extent of 3" 6'". The deeper part 

 of the alveolus is distinct for the anterior teeth ; but as they recede the 

 sockets are indicated by depressions merely in the common groove. 

 The teeth are slender cones." 



See also 

 1. PDelphinus Feres, Bmnat. Cetac. 27; Gray, Cat. Cetac. B. M. 1850,91. 

 Blackish ; teeth \^, large and small, curved, compressed before 



