THE SOUTHERN SEA LION 281 



in a mixture of roars and coughs and the breath is expelled with great force, as I have 

 observed from a position close enough to feel the breath on my face. The cloud of 

 steam emitted in cold weather is remarkable for size and volume. The pitch of the 

 voice is about that of the lowest D on the piano. The bulls grunt and groan a good 

 deal besides roaring. The female has a strong voice, rather resembling that of a large 

 domestic calf and about the same pitch, while the pup has a high-pitched, sheep-like 

 bleat. All stages emit snarling noises when fighting. 



DEVELOPMENTAL STAGES OF THE SKULL 

 During these investigations 82 skulls were collected (Table I). Most of them were 

 from animals specially killed, but a few were from seal found dead, but fresh, on the 

 beach and one was taken from an adult male which had been dead for a considerable 

 time but of which the skeleton was still intact. One skull was secured in Stanley from 

 a bull which had been killed some years before, so that place and date were available 

 but no record of the total length. All the skulls were prepared by being boiled as soon 

 as possible, a proceeding which was necessitated by the extreme difficulty of drying 

 meat in the Falklands and by the need to make preliminary examinations as a guide 

 to future researches. 



The development of the skull is rather different in the two sexes, which will therefore 

 be considered separately ; but in both there is an increase in zygomatic width relative 

 to the length of the skull, from the fourth year onwards. Since skulls which are 

 completely ossified are of different sizes it follows that the size at which growth ceases 

 varies with the individual. 



Male skull 



The number of male skulls collected was 46 (Table IV) and in addition 21 skulls of 

 adult males in the British Museum (Natural History) and the Museum of the Royal 

 College of Surgeons have been examined (Table III). Of the skulls which I myself 

 collected the majority were obtained between June 8 and July 29 ; among the others 

 are an adult and a sub-adult male, killed on January 17, another adult killed in 1923, 

 and an almost new-born pup found dead on January 4. Unless specifically mentioned 

 the sub-adult male and the pup are left out of account. 



An examination of the series of skulls shows that each of the six stages has its own 

 osteological characters, a statement which applies to both sexes. The measurements 

 in Table II and in Figs. 3, 4 are the averages for the groups of skulls in each stage. 



In the FIRST YEAR the average length of the skull is 195-6 mm., 16-3 per cent of the 

 body length ; the zygomatic width is 108-3 rnrn., being 55-4 per cent of the skull length ; 

 and the distance from the tip of one of the hamular processes to the end of the pre- 

 maxillae is 123-5 rnm., 63-1 per cent of the length of the skull. The skull is in general 

 smooth all over and obviously juvenile in character. There are still traces of the sutures 

 of the occipital segment; the suture between the basi -occipital and the basisphenoid 

 is open and all the sutures are simple. There is a depression in the middle hne just 



