246 



HARDWICKE'S SCIENCE-GOSSIP. 



a drawing showing this stage ; but I doubt if any 

 one ever saw them drop off or cast their tails. Yet 

 so widespread is this popular delusion, that even at 

 the late Microscopical Soiree of the British Asso- 

 ciation at Bristol, learned members, showing the 

 circulation in frogs' feet and tadpoles' gills and 

 tails, were patiently propagating the favourite fact. 

 When asked to prove it, the answer was, "Every 

 one knows it." When asked, had any one ever seen 

 the tails drop off? the only answer was a surprised 

 look of incredulity, as if the interrogator had gone 

 mad. How this odd superstition arose and became 

 so widely disseminated by word of mouth and in 

 print, is hard to say. 



This instance again shows how little we know 

 even of our commonest aquatic animals, and how 

 much remains to be learnt. Aquarium science, yet 

 in its infancy, will add important links to our know, 

 ledge, especially in the study of embryology. But in 

 the case of toads and frogs, a large public aquarium, 

 with constant circulation of water, is not necessary. 

 Any one with a little common sense and patience 

 can keep tadpoles. It would be extremely inter- 

 esting to get a careful set of observations, with 

 locality, names, dates, and drawings of the com- 

 parative development from embryo to adult of the 

 common frog {Rana temporaria), the two toads 

 (Bnfo vulgaris and B. calamita), and also our water 

 salamanders, tritons, lizards, or newts {Triton 

 aquations and T. cristatus). I should be glad to 

 know who is considered the best authority on this 

 subject, and if a series of correct drawings exist. 

 Also I want to know if toad tadpoles ever possess 

 external gills ? My drawings do not represent any ; 

 in other respects they resemble the frogs : both 

 tadpoles live from about March to August. I have 

 never hatched-out water-lizard tadpoles, but have 

 drawings of four taken Sept. 20, 1860, representing 

 them of different sizes and stages, from half an 

 inch long, with four legs and external gills, to 

 li inch, with four legs, a tail, and no external 

 gills ; that is, exactly like the adult, but not fully 

 grown. I saw a specimen as large as this, showing 

 the beautiful circulation of the blood through the 

 external gills, last mouth, at the British Association 

 soiree, Aug. 26. Thus, it appears, as if these young 

 water-lizards are of different ages, and therefore the 

 eggs must be laid at different times. Is this so ? 

 J. G. Wood says that the water-lizards {Triton) lay 

 their eggs separately ; each single egg is deposited 

 on some water-plant, and that then the leaf is 

 cleverly twisted up so as to protect and conceal it. 

 H. A. Nicholson, in his " Manual of Zoology," dis- 

 tinguishes between the order Urodela, or tailed 

 amphibians, such as water salamanders or tritons, 

 and the Anoura, or tail-less amphibians, as frogs 

 and toads, by saying that " the development of the 

 newts is like that of the frogs, with two points of 

 difference. 1st, that the embryonic tail is not cast 



off in the adult ; and 2nd, that the fore limbs are 

 developed sooner than the hind limbs, the reverse 

 being the case in the Anoura." The water sala- 

 manders, or newts, are furnished with a compressed 

 fish-like tail, and are strictly oviparous (that is, the 

 young are hatched from eggs). The larvae are tad- 

 pole-like in form, with external branchiae, which 

 they retain till about the third month. The adult 

 is destitute of gills, and breathes by lungs alone, 

 but the larval tail is retained throughout the life of 

 the animal. The land salamanders form the genus 

 Salamandra, and are distinguished from their 

 aquatic brethren by having a cylindrical instead of 

 a compressed tail, and by bringing forth their young 

 alive, or by being ovo-viparous. The water newts 

 and all the Urodela are often completely lizard-like 

 in form when adult, but they always possess gills 

 in the earlier stages of their existence, and this 

 distinguishes them from all the true lizards {La- 

 certitia). These are related to the giant extinct 

 Saurians. 



Thus we have in the frog an animal furnished 

 with three sets of breathing apparatus, four legs, 

 and a tail at different stages of its existence. 1st, 

 external gills as a tadpole ; 2nd, .internal gills like 

 a fish ; 3rd, lurgs adapted for breathing air. The 

 gills and tail, no longer needed for aquatic existence, 

 are absorbed, not lost ; the animal steps out of the 

 water a true lung-breathing vertebrate. Next come 

 the Tritons, with external gills for three months in- 

 stead of three days ; lungs appear, and the four legs 

 and tail are retained throughout life. The animal is 

 amphibious, living mostly in the water, but dies for 

 want of breath if kept there, and prevented from 

 coming to the surface to breathe. Next below 

 comes a curious animal, the American Axolotl 

 {Siredon pisciformis), shining like a huge black 

 tadpole 12 or 14 inches long, with four legs, a 

 tail, and a set of external gills, which are retained 

 throughout the whole of its existence. For some 

 time it was supposed to be merely the tadpole, or 

 larval form of some terrestrial animal, but I believe 

 it is never known to leave the water voluntarily, 

 and breeds freely in this condition, laying quantities 

 of eggs, which are easily reared. Strange to say, 

 although it never breathes by anything but gills, it 

 has rudimentary lungs. This tendency to variation, 

 and shadowing forth of higher forms, side by side 

 with persistent types, is intensely interesting, as 

 forming links in Darwin's endless chain of evolution. 



G. S. 



THE "WEARING" OF LEPIDOPTERA. 



TT is a fact which must have been noticed by 

 ■*- all collectors of Lepidoptera, that there is a 

 remarkable tendency in some species speedily to 

 become worn and torn. As a notable instance of this 

 I may mention the graceful Limenitis Sibylla. For 



