i 2 6 DISCOVERY REPORTS 



A few foetuses of moderate size were found, but search for the very early (blastocyst) 

 stages was not feasible in the circumstances. 



Bouin's (aqueous) picro-formol has been used for all histological material and has 

 proved exceedingly good, possessing, as it does, great powers of penetration. The 

 subsequent sections were stained with Ehrlich's haematoxylin and eosin, or Weigert's 

 iron haematoxylin followed by van Gieson's picro-saurefuchsin. Histological measure- 

 ments were made with a micrometer eyepiece. 



OSTEOLOGY 

 MALE SKULL, GIANT SPECIMEN 



There are no additional observations to be made on the normal skull of the adult 

 male, but no. "393 " calls for some notice (PI. XXVI). 



This specimen, found along with one ramus of the mandible among the scattered 

 bones of the skeleton, was collected on account of its large size and proved to be the 

 largest male skull of which I have a record. The length is 393 mm., the zygomatic 

 width 251 mm. and the hamulo-premaxillar length 285 mm., exceeding the previous 

 maxima of these dimensions by 11-9 and 15 mm. respectively. The crests are of great 

 size, and the whole skull is remarkably massive, weighing 3750 g. ; four large skulls in 

 the British Museum weigh 2000-2450 g., with an average of 2200 g. 



All the sutures are obliterated, except those of the nasals, the dorsal part of the maxillo- 

 frontals and the junctions of the squamosals and jugals, but the latter are well fused. 



The dental part of the premaxillae and maxillae are greatly enlarged by growth of 

 hard cancellous bone, which strongly suggests that it is the result of an inflammatory 

 condition ; and of the twelve cheek teeth seven are missing, presumably post-mortem. 

 Two are in moderate condition and three are mere fragments, one of which is partly 

 overgrown with bone; the four middle incisors have all been lost and their alveoli 

 obliterated. The canine of the mandible (right) is very blunt and worn. The remaining 

 teeth are missing, but all of them post-mortem except the first incisor. 



Similar proliferation of cancellous bone but on a very limited scale is not uncommon 

 in large males of Otaria, and although no preserved material is available for examination 

 it may be suggested that the condition may possibly result from infection which has 

 found an entrance through injuries to the mouth received in fighting, and such injuries 

 are very common. 



FEMALE SKULL, DEVELOPMENTAL STAGES OF ADULT LIFE 

 The series of skulls from sexually active females numbers 93 and covers the period 

 from the first ovulation to what is, almost certainly, senility. Seventy-two of them were 

 collected during the period 1934-7 and 21 belong to the earlier series (1930-2). Since 

 the number of specimens of the sixth year or older is now 58 instead of 1 1, it is possible 

 to identify age groups additional to those described in 1934, and therefore a revision of 

 the statement made on p. 290 of the report of that date is necessary. Skulls of the 

 fourth to tenth year groups are illustrated in Pis. XXVII, XXVIII and XXIX. 



