ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 407 



land-snail faunas, which are shown to be : — (1) nearly homogeneous over 

 vast areas ; (2) composed of ancient types, with no admixture of the great 

 series of modern families; and (3) not derivable from any tertiary or 

 modern continental fauna or faunas in the sense Atlantic island faunas 

 have been derived. The molluscs, land and marine, supply no evidence 

 that this Pacific continent was ever connected with, or faunally affected 

 by, the Americas, but emphatically contradict such connection. 



Eyes of Cave Animals. * — Prof. C. H. Eigenmann sums up some of 

 his previously recorded results in a general paper on the degeneration 

 of the eyes which occurs in North-American cave salamanders and 

 cave fishes (Amblyopsidfe). He discusses in detail the structure of the 

 different parts of the eye in these forms, and in regard to the nature of 

 the degenerative changes, comes to the following conclusion : — " The 

 adult degenerate eye is not an arrested ontogenic stage of development, 

 but a new adaptation, and there is an attempt in ontogeny to reach the 

 degenerate adult condition in the most direct way possible." 



Variations in Vertebral Column of Man. f — Dr. T. Dwight, at 

 the close of his study on this subject, formulates six conclusions 

 (1) Variations occur in two ways : — (a) by irregular development of the 

 costal elements at and near the ends of the regions of the spine ; (&) 

 by irregular segmentation, through which there are more or fewer 

 vertebras than usual. (2) Variations of both kinds are variations 

 around a mean. It is not impossible that some of them may be 

 reversive ; that any are progressive is a mere assertion. (3) Assuming 

 the correctness of Rosenberg's studies in ontogenesis, his view (the 

 notion of changes of position of the ilium and the consequent modifica- 

 tion of vertebrae according to the position it finally assumes) may 

 account for some of the variations, but even in these cases something 

 more is needed to explain the concomitant changes. (4) Variation of 

 the costal elements at one end of a region is often associated with 

 variation of an opposite nature of those at the other end. Several 

 regions may be involved, and the two sides may vary independently. 



(5) Variations, which separately seem either reversive or progressive, 

 generally lose that appearance when the whole spine is considered. 



(6) After the occurrence of the original error in development there is a 

 tendency for the spine to assume, as nearly as possible, its normal dis- 

 position and proportions. This implies a vital principle, as do also 

 concomitant variations, and, indeed, all development. 



Variation in Chelopus insciilptus.j — Prof. G. H. Parker describes 

 two abnormal specimens of this American tortoise, in which both the 

 scutes and the bony plates showed variation. The general interest of 

 the paper is that it tends to show that the variations in scutes and plates 

 are correlated, and that the connection between the two is much closer 

 than has been hitherto supposed. 



Variations of the Toad.§ — Prof. L. Camerano has published an im- 

 portant and elaborate study of the variations of over a score of characters 



* Proc. Indiana Acad. Sci., 1899, pp. 31-46 (9 figs.). Cf. this Journal, 1899, 

 p. 273. t Anat. Anzeig., six. (1901) pp. 337-47 (3 figs.). 



J Amer. Nat., xxxv. (1901) pp. 17-24 (5 figs.). 

 § Mem. R. Accad. Sci. Torino, 1. (1901) pp. 81-153 (2 pis.). 



