—_—— 
1864.] DR. J. E. GRAY ON DACTYLETHRA. 46] 
they are in others; but I suspect this depends on the season when 
the specimen has been captured, and especially on the state and 
manner in which the specimen has been preserved. 
The specimens in spirit rather vary in colour; but this may de- 
pend on the length of time that they have been in spirit, on the 
exposure to which they have been submitted, and on the strength 
of the spirit in which they were originally preserved. 
The specimens of an adult male and female from West Africa, 
presented by Mr. Welwitsch, are of a uniform olive-brown above and 
yellowish below, marbled with very distinct, unequal-sized, subsym- 
metrically distributed olive spots. 
The specimen from the Cape, presented by Sir Andrew Smith, 
which is in a rather soft state, is olive obscurely spotted above, pale 
whitish grey beneath, obscurely marked with small darker spots. 
The adult specimen from Natal, collected by Mr. Ayres, and the 
smaller specimen from West Africa are of a uniform olive-brown 
above and pale grey-brown beneath, without any indication of spots. 
Mr. R. B. N. Walker (to whom we are indebted for the best ac- 
count of the habits of the Gorilla, and who has brought to England 
some most interesting animals from Western Africa) has lately been 
living at Lagos, where he observed some Tadpoles that were deve- 
loped in abundance in a pond adjoining his residence. He put some of 
these in spirits, and gave them to the Free Museum at Liverpool. 
Mr. Moore having kindly sent me some of these specimens for exa- 
mination, I was soon convinced that they had not before been ob- 
served, and therefore sent a short notice of them to the ‘ Annals and 
Magazine of Natural History’ for September 1864, and named them, 
from their resemblance to the genus Stlurus, Silurana tropicalis. 
Some naturalists having expressed a doubt if the animals sent 
