REPORT ON THE SEALS. 35 



Allen in his important monograph above referred to. It may suffice to state that Dr. 

 Gray, in his latest writings 1 on this subject, spoke of four species, viz., Otaria jubata, 

 Otaria minor, Otaria ulloas, and Otaria pygmsea; whilst Dr. Peters, in his last published 

 paper, 2 recognised only one species, viz., the Otaria jubata of Forster. Peters regarded the 

 Otaria leonina of Fr. Cuvier, and the Otaria ullose of Tschudi, merely as " Localrassen," 

 whilst he made no mention of the Otaria godeffroyi which he had described in May 

 1866 3 as a distinct species, so that he doubtless ultimately considered it also as only a 

 variety of Otaria jubata. The geographical distribution of Otaria jubata is said by 

 Peters to extend around the southern half of South America, from Rio de la Plata on 

 the east to Callao and the Chincha Islands on the west. Mr. Allen also favours the 

 view that Otaria jubata is the only species, and in addition to its habitat on the South 

 American continent, assigns it to the Galapagos Islands in the Pacific, from specimens 

 collected by the Hassler Expedition, whilst the crania collected by the Challenger, and 

 others previously procured, have established it to be a denizen of the Falkland Islands. 



If it be correct to regard the genus Otaria as consisting only of the species jubata, 

 then it will follow that all the crania which I have described in this section, notwith- 

 standing their great difference in size, and to some extent in proportion, are to be 

 considered as of this species, and the small adult skulls would then be females, whilst 

 the larger crania would without doubt be males. Dr. Murie, in his monograph on the 

 Sea Lion, has given the following dimensions of crania which he has measured. In an 

 adult female the skull was 11 inches long (280 mm.), and 5 - 8 inches broad (148 mm.) ; 

 an old male was 12"8 inches long (325 mm.), and 7'5 inches broad (190 mm.), and a 

 very old male 14*3 inches long (363 mm.), and 9"4 inches broad (239 mm.). Mr. Allen 

 records the mean length of eight male skulls at 350 mm., and the mean breadth 223 mm., 

 whilst the mean length of four females was 261 mm., and the mean breadth 143 mm. 

 These proportions closely approximate to the measurements of the adult male and female 

 crania which I have given in Table IV. Mr. Allen also states that there is a wonderful 

 disparity in size between the sexes in Otaria jubata, the weight of the adult males being 

 generally three to five times that of the adult females. 



The length-breadth indices of the two large male skulls, calculated on the interzygo- 

 matic breadth, were respectively 64 - 3 and 61 - 9, and on the width behind the external 

 meatus 59"4 and 57'5. The corresponding indices in the smaller adult from Maldonado 

 were 60"3 and 49, and in the young skull 60'2 and 55*9. The difference between the 

 interzygomatic width and the width behind the external meatus was most strongly 

 marked in the Maldonado cranium. 4 



1 Ann. and Mag. Nat. Hist., ser. 4, vol. xiii. p. 325 ; and Hand Atlas of Seals. 



2 Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, August 9, 1877, p. 506. 3 Op. cit, May 17, 1866, p. 266. 



4 I have not thought it necessary to figure the skull of Otaria jubata, as Dr. Murie's memoir on this animal is so 

 completely illustrated. 



