I!Y LAUXCELOT HARRISOX. 373 



Here again it seems imjjossible that the piginent of. the egg should have Ijeen 

 produced in response to the direct stimuhis of light, and a supposition that 

 Pseu-dophrijne has only recently taken to a cryptozoic liabit, and has not yet 

 succeeded in eliminating ]iiginent, hardly heljis matters. 



Regarding the pigmentation of tadpoles, I can confirm the observations of 

 Wenig (1013) that those which develop in water with clay in suspension do not 

 develop normal pigment. I recently captured some tadpoles of Limiwdynastes 

 at a depth of five feet in a muddy creek, in a net sunk for crayfish. The normal 

 tadpole h.T-s a uniform dense pigmentation, but these individuals were almost 

 transparent, except for two lines of eiiromatophores dorso-laterally along the 

 main muscle mass, and the whole brain showed white through the dorsal sur- 

 f.ace. Here tliere has been an obvious relation between light and pigment 

 development. 



For the eggs, liowevcr. the matter is apparently not so simple, and an en- 

 quiry into the nature and mechanism of production of these pigments, and into 

 the purpose tliey subserve, seems called for. 



List of Works Beferred to. 



Agar, TV. E., 1909. — Tlie Nesting habits of the Tree-frog, Phyllomedusa saiivagH. 



Proc. 7moI. Soc. Lontl. 1909, pp. 893-897, PI. Ixxxiv. 

 Bles, E. .J., 1907. — Notes on Anuran Development, in Tlie Work of John 



Samuel Budgett, Cambridge, pp. -143-458, PI. xxii.-xxvii. 

 BUDGETT, .1. S., 1899. — Notes on the Batrachians of the Paraguayan Chaco. 



Quart. Journ. Blicr. Sci.. xlii., pp. 305-333, PL xxviii.-xxxii. 

 Dakin, W. J., 1920. — Notes of the Habits and Reproduction of the Great 



Western Burrowing Frog, Heleioporw albopunctatus. Anstr. Zoologist, L, 



l)p. 241-244. 

 Kerr, J. G., 1919. — Text-Book of Embryology, Vol. ii., Vertebrata. London. 

 Morgan, T. H., 1891. — Some Notes on the Breeding Habits and Embryology of 



Frogs. Amer. Nat., xxv., pp. 753-7()0. 

 Wexig; J.. 1913. — Der Alhinismus bei den Anuren, etc., Anat. Am., xliii., pp. 



113-135. 



