Dr. A. Giinther on a new Siluroid Fish from Ceylon. 478 
that this liquid is contained im a little box, of which the anterior 
and posterior surfaces are made of thin glass. 
The numbers which I have obtained in the same medium and 
for the same individual are very close, which justifies our having 
confidence in the results of experiments so delicate ; but, more- 
over, as may be seen from the table which I give in my memoir, 
the distances of distinct vision in the air and in water are always 
very nearly the same. Fishes, therefore, as I have already said 
from the consideration of the structure of the eye, see as well 
in the air as in water. 
Hence, also, the vision of Amphibia finds a natural explana- 
tion, as the visual organs of those animals resemble those of 
Fishes. Nevertheless, as a confirmation of the theory, I have 
subjected to the same experiments the eyes of some Batrachia ; 
and in these also the distances of distinct vision in air and in 
water are, so to speak, identical. I shall only remark, in con- 
cluding this analysis, that, in the Amphibia, distinct vision, which 
is necessarily very short in water in consequence of the imper- 
fect transparency of that medium, must, on the contrary, be able 
to extend itself in the air to very variable distances, which ne- 
cessitates the existence of a faculty of accommodation; and ac- 
cordingly the presence of the ciliary muscle, the chief agent of 
that faculty, has been recognized in their eyes. 
LX.—Description of a new Siluroid Fish from Ceylon. 
By Dr. ALBERT GUNTHER. 
[Plate XV.] 
A sMALL collection of freshwater fishes, made by the Rev. Ban- 
croft Boake in Ceylon, and kindly submitted to my examination 
by F. Layard, Hsq., contained two Siluroid fishes of the genus 
Arius, which are of great interest, inasmuch as they prove that 
the peculiar habit which I have described in an American species, 
A. fissus (Fish. v. p. 178), viz. the mode in which the parent fish 
takes care of its progeny, is not confined to South-American spe- 
cies, but exists also in the East-Indian ones. The mature ova are 
of the same large size in all these fish ; and in all it is the male 
which carries them in the spacious cavity of its mouth. Accord- 
ing to Mr. Boake, who has published an account of the habits 
of these fish, they are called Angaluwa. Three specimens were 
in the collection, belonging, however, to two very distinct 
species, new to science. Two of these, a male and a female, 
14 inches long, are Arius Boakii, so named by Mr. W. Turner, 
who also had received examples, and read an account of them 
at the last meeting of the British Association. We may there- 
