28 INTRODUCTION. 



esculenta feebly pigmented; and of black tadpoles, 

 or of a dark brown approaching black, I only know 

 Bufo and liana temporarla; all tho other European 

 species are only exceptionally, not normally very dark. 

 That the light cannot have a great effect in producing 

 the pigment in Batrachian larvae is shown by Alytes 

 and Bombiuator, both of which develop the same 

 amount of pigmentation, the one under paternal care 

 never being exposed to daylight, the other reared in 

 pools or puddles exposed to the full action of the sun's 

 rays. 



Cases of melanism, or better, absence of iridocytes 

 and all pigment but the brown or black, which may be 

 very abundantly and exclusively present, have been 

 observed by Heron-Royer in Alytes obstetricans, by 

 Alfred Duges, and more recently by Heron-Royer and 

 by Vaillant, in liana esculenta. I found a similar 

 young specimen of the latter species in a marsh near 

 the Belgian coast in 1884; the back was brown, 

 nearly black, the hinder side of the thighs and the 

 ventral surface pigmentless, transparent flesh-colour, 

 the iris black without any gold. A male specimen of 

 Bana grseca from Italy, showing the same abnormality 

 in the absence of all but the brown colour, was sent 

 to me last spring by Count Peracca, and is figured on 

 Plate XXII of this work. 



Albinism, or absence of the brown pigment, on the 

 other hand, has been observed in a young Bombiuator 

 pachypus by Fatio, in larva3 of Alytes obstetricans by 

 Lataste and Heron-Royer, who succeeded in rearing 

 them through the metamorphosis, in a larva of Disco- 

 c/lossus p ictus by myself, in liana esculenta by Pavesi, 

 in larvae and young of Bufo viridis by Born, Camerano, 

 and myself, in larvae of Bana temporarla by Lessona, 

 Fischer-Sigwart, and Camerano ; an adult female of 

 the latter species found in England was exhibited 

 alive by Mr. Rowland Ward at the Linnean Society 

 in 1891, and another, from Wiltshire, presented by 

 Mr. W. Hannaford, is now preserved in the British 



