40 PKOFESSOR OWEN ON INDIAN CETACEA. 



ing downward and forward : the surface is rather convex at the anterior border from 

 behind forward, and is veiy slightly concave in the rest of its extent ; it is smooth and 

 with an ill-dcfincd cucumference : the anterior boundary, which also forms the posterior 

 one of the lower outlet of the temporal fossa, is concave : the wall (PI. XII. fig. 1, 27') which 

 the squamosal contributes to the posterior and internal part of the temporal fossa (t) 

 expands as it bends forward to join the parietal (?) and fi-ontal (11): the suture with 

 the superoccipital ( 3 ) is close to the upper boundary of the fossa ; that with the 

 exoccipital ( 2 ) contmues a short way beyond the squamosal, and indicates the extent of 

 the exoccipital. On the outer part of the base of the zygomatic or articular process the 

 bone is tuberous, and represents the mastoid ( 8 ) ; behind the articular sm-face it is 

 roughly excavated (PI. XIII. fig. 2, s), where it contributes, with the paroccipital (*), 

 to the otocranial cavity ^ 



In the interior of the cranium (PI. XIV. fig. 1) the upper or epencephalic surface of 

 the basioccipital is moderately concave, and is bounded laterally by a short, obtuse, longi- 

 tudinal ridge, dii-ccted mesiad, which may be where the exoccipital suture ran : the outer 

 or lateral beginning of the tentorium receives a short angular ossification, which forms 

 the outer waU of the fossa (v), perforated by the vagal and acoustic foramina, both of 

 which pass directly outward to that at the back part of the fundus of the otocranial 

 cavity (PI. XII. fig. 1, PI. XIII. fig. 2, e). A small branch chaimel from the vagal one 

 opens upon the outer surface of the exoccipital at the groove which runs to the cleft 

 (PI. XII. fig. 2, 1) between the otocranial plates of the basisphenoid (5) and paroccipitals 

 (4). At the fore part of the tentorial process (PI. XIV. fig. l,v) is the foramen of 

 a canal which opens outwardly upon the alisphenoid : it is too small for the carotid, and 

 may have given exit to a vein. I cannot discover any distinct cntocarotid canal, any 

 more than a distinct foramen ovale, foramen rotundum, or foramen opticum : they all 

 seem here to be confounded in the intersphenal fissure (PI. XIII. fig. 2, fr). From the 

 extreme shortness of the jaws, the nerves of sensation to the face must have been very 

 small. The " sella" (PI. XIV. figs. 1 & .3), scarcely impresses the basisphenoid : its best 

 antero-extemal boundaries are afibrded by the superoptic processes of the orbitosphenoid 

 (ib. «). There is no ossification of the falx^, no trace of olfactory foramina. The great- 

 est diameter of the cranial cavity is ui the direction of breadth. 



The lower jaw (PI. XII. fig. 1, 29-32) is 7 inches 4 Imes ui a straight line from the back 



' " The squamosal is a comparativel)' small, but strong and thick, triangular bone ; the upper end repre- 

 sents the expanded squamous part in land mammals, and is articulated by broad, dentated sutural margins to 

 the frontal and exoccipital : its anterior border is grooved for the reception of the alisi)henoid : the lower angle 

 is as it were trancated, and presents a rough surface for the attachment of the petro-tympanic : a short, 

 obtuse anterior angle bends forward and represents the zygomatic process : the under surface presents a 

 smooth shallow cavity for the condyle of the lower jaw : the inner border of the glenoid surfcice is proQuced 

 downward into a slender process." — Physctcr macrocephalus, op. eit. p. 444. 



' In the Great Cachalot " a strong medial crest is produced forward from the inner surface of the super - 

 occipital" {Joe. cit. p. 442). 



