27 



■it may be absent in some specimens, whilst, on the other hand, it 

 may be present in the othei' species, the Edible Frog {B. escidenta). 

 This second frog used to be common in the Cambridgeshire Fens, 

 and is still found in a few localities in Norfolk ; it has certainly 

 been in existence in these places for a great number of years, but 

 whether it is indigenous or introduced from the continent, no one 

 can say. Such as it occurs in this country (var. lessoncr) it is easily 

 distinguished from the Common Frog by the presence of a yellow 

 or green stripe along the back, the bright yellow and black marblings 

 on the groin and buttocks, the large, hard, compressed tubercle at 

 the base of the inner toe, and the presence in the male sex of an 

 •external vocal sac on each side of the head, protruding, when in- 

 flated, through a slit below the ear ; this bladder-like vesicle is of 

 the size of a small cherry in full-grown individuals. The croak is 

 very loud, but quite different from that of the Natterjack, consisting 

 of a variety of notes, and, unlike the toad's, is produced in the day- 

 time as well as at night. 



The eggs of the Common Frog are very conspicuous in late winter 

 or early spring as large masses of jelly enclosing small black spheres 

 (the ovum proper) in countless numbers, floating on the surface of 

 'the water; those of the Edible Frog are never seen, as they sink to 

 ihe bottom, and they are not laid until June. The eggs of toads are 

 very different, forming long strings, comparable, rigidity apart, to 

 glass tubes, containing small black beads in single or double file. A 

 few years ago, on the occasion of a communication on distant 

 orientation in Batrachians by that highly promising young zoologist, 

 B. F. Cummings, whose recent loss we deplore, I made some remarks 

 on the habits of our Frogs and Toads, which I will here reproduce 

 from the Zoological Society's " Proceedings," by permission of the 

 Society. 



" There is great diversity among Tailless Batrachians in the pos- 

 session, lack, or degree of instinctive foresight in selecting places 

 for the deposition of their eggs. Leaving out the thoroughly 

 aquatic Edible Frog, which has only doubtful claims to be regarded 

 as British, two of our species, the Common Frog and the Natterjack 

 Toad, belong to the category of the least gifted in this respect, 

 whilst the third, the Common Toad, behaves differently, and is 

 besides possessed of an instinct for orientation which appears to be 

 highly developed. The fact that, after the perfect condition is 

 attained. Tailless Batrachians, unlike the Tailed, do not regenerate 

 lost parts, would render the Common Toad further suitable for 

 experiments on migrations, after the amputation of a finger or toe, 

 as a distinctive mark. The Natterjack is, with us, a very local 

 species, but the Common Toad and the Common Frog are ubiquitous 

 and, as young or outside the breeding-season, are often found far 

 from water, to which they have, of course, to resort for oviposition. 

 How the three species behave in connexion with this function I will 

 tell briefly from my own observations. 



