240 NATURAL SCIENCE. %^: 



A young male sea-lion, possibly Otaria stelleri, a species found 

 also off the coast of California, was purchased two years ago. It was 

 about a year old at the time, docile, and very intelligent, and soon 

 became a most finished performer. This animal, of a dark reddish- 

 brown colour, with prominent eyes, has not yet acquired its full 

 dentition. There are seven teeth in each upper jaw, but no signs of 

 the prominent canines characteristic of the Patagonian sea-lion 

 Otaria jubata. 



The oldest captives are the sterlets [Acipenser ruthenus), first 

 brought over from the Volga shortly after the Aquarium was opened 

 nearly twenty years ago. Next in seniority is the Alligator Terrapin, 

 from America [Chelydya serpentina) which has passed thirteen years of 

 uneventful existence in congenial warm waters. Less than a foot 

 long on arrival, it now measures between four and five feet from beak 

 to tail, and its double ridged carapace is broad in proportion. 



Agnes Crane. 



The Wrestler Frog of La Plata. 



Mr. W. H. Hudson, in his " Naturalist in La Plata," reviewed 

 in the last number of this journal, relates his experience with a frog, 

 which, instead of attempting to escape, sprang at and caught hold of 

 the fingers of its pursuer. The frog was no doubt a breeding male of 

 the common Leptodactyliis hnllatus. Our toad behaves just the same in 

 early spring, and many males can be secured from the ponds, where 

 they congregate for the purpose of breeding, by the simple method of 

 holding out to them a walking stick which they will clasp in the 

 manner witnessed by Mr. Hudson. But what is more extraordinary 

 is to find our common frog [Rana teniporaria) figured as the " Wrestler 

 Frog " of La Plata, for no species of the genus Rana, nor any repre- 

 sentative of the family Ranidae, has yet been found in the Argentine 

 Republic. As the specimen observed by Mr. Hudson was not pre- 

 served, the figure was probably executed at home from a British 

 specimen. This reminds us of a similar want of accuracy in one of 

 Gould's works, where an Australian bird is depicted in the act of 

 seizing a newt. G. A. Boulenger. 



EXALLAGE. 



In my article on Life-Zones in Lower Palaeozoic Rocks, last 

 month, I was in error in assigning a remark to Dr. Blanford con- 

 cerning the desirability of a term for "time- varieties." Dr. Blanford 

 has kindly called my attention to the account of a discussion in the 

 Report of the International Geological Congress, held at Bologna 

 in 1881 (Report, p. 168), in which the term " mutation " is suggested 

 in the same sense as that in which the word " Exallage " was used 

 in my article. I wish, therefore, to withdraw the term Exallage, 

 though I still think the word " Exallagous" (not Exallogous) may be 

 useful as an adjective. J. E. Marr. 



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