ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 2D 



themselves by alertness (Chcetodon, Pomacentrus) or by burying them- 

 selves in the sand (e.g. Jules gaimardi), a habit more frequent than has 

 been suspected. The author also alludes to variability in coloration. 



Arsenic in Animals.* — G. Bertrand has found minute traces of 

 arsenic in a large number of animals — sponge, sea-anemone, starfish, sea- 

 urchin, holothurian, barnacle, sepia, fish, turtle, stormy petrel, and Orca 

 gladiator. In most cases it was diffusely distributed. 



In an appended note Gautier remarks that in his researches on 

 terrestrial mammals and on birds, the arsenic was mainly restricted to 

 the ectodermic structures. He found it also in marine and fresh- water 

 green algas, and he is convinced that the sea-water is itself arsenical. 



Rabbit Pest in Australia.f — W. Eodier has reprinted a useful 

 pamphlet, which was noted in Nature, March 21, 1889, explaining a 

 simple method of dealing with the rabbit pest. His plan is based on the 

 fact that while polygamy favours increase, polyandry does not. Rabbits 

 usually live in a polygamous state. Rodier proposes to convert this into 

 polyandry by catching the rabbits alive and killing all the females, while 

 all the males are turned out again. The males become much more 

 numerous, they harass the females by their constant attentions, they 

 injure their powers of breeding. The plan has worked well at Tambua 

 station, Cobar, N.S.W., and surely deserves a trial, since all other 

 methods have been more or less failures. 



Origin of Paired Limbs of Vertebrates.^ — Bashford Dean considers 

 the historical or palasontological evidence. As regards Palaeozoic sharks, 

 it is most distinctly in favour of the Thacher-Balfour theory of deriva- 

 tion from lateral folds. The oldest forms, acanthodians and cladosela- 

 chids, present lateral-fold fins. As the series advances from the lower 

 Devonian, the structures of the biserial archipterygium are gradually 

 acquired. The Carboniferous Cladodus neilsoni of Traquair shows for 

 the first time a definite segmentation of the supporting elements of the 

 base of the pectoral fin. Then in the Permian Symmorium of Cope, the 

 fin-bases are not only formed, but show apparent fusion in the meta- 

 pterygial terminal, a condition which would be best correlated with a 

 change of function in the fin. And finally, in the Xenacanthids, the 

 pectoral fin acquires a biserial archipterygium. 



The author considers the objections to this conclusion, and points 

 out the difficulties of Gegenbaur's theory. 



Interscapular Gland in Human Embryos. — Shinkishi Hatai has 

 found in five human embryos a long, .narrow, paired organ, lying partly 

 along the neck and partly occupying the scapular region. It has no 

 anatomical connection with the thymus. No trace of it was found in 

 the adult. From its position, as well as from its fatty structure, it seems 

 comparable to the so-called hibernating gland or fat-organ of lower 

 mammals, but on the other hand, the lymphoid structure which seems 



* Comptes Rendus, cxxxv. (1902) pp. 809-12. 



t ' The Rabbit Pest in Australia, its Cause and Cure,' Sydney, 8vo, 16 pp. See- 

 Nature, lxvii. pp. 43-4. 



% Amer. Nat., xxxvi. (1902) pp. 7fi7-76 (1 fig.). 

 § Anat. Anzeig., xxi. (1902) pp. 369-73 (3 figs.). 



