ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 517 



non-accidental variation has affected the growth of the bony tissue of 

 the lower jaw and of the left side of the skull, and has resulted in 

 marked asymmetry. 



Monograph of Genus Dendrocincla.* — H. C. Oberholser finds that 

 individual colour variation is very marked in some forms, occasionally 

 amounting to a greater degree of difference than that distinguishing 

 some species. The sexes, though alike in colour, frequently differ widely 

 in size. The colour of the bill, which some writers have relied on to 

 furnish specific distinctions, seems to change with age. The paper con- 

 tains an account of the characters of the species and sub-species, which 

 will help to clear up the uncertainty hitherto attending the identification 

 of the birds of this genus. 



Eyes of a Blind Snake.f — Effa Funk Muhse describes the structure 

 of the eyes in Typhlops lumbricalis, a blind burrowing snake generally 

 distributed in the West Indies and Guiana, living just beneath the 

 surface and often thrown out by the plough. The eye shows through 

 the large ocular scale, which entirely covers it. It appears as a black 

 spot surrounded by an unpigmented circle. The usual parts are present : 

 a cornea, an iris, ciliary processes, a large lens, and a retina with the 

 same layers as in snakes in general. The peculiarities are in details of 

 the retinal layers. 



Osmotic Properties of Amphibian Skin.| — F. Overton has demon- 

 strated various points bearing on this subject. For example, he finds 

 that in tree-frogs water may be absorbed through the skin, and that for 

 equally large skin surfaces of the same region of the body under like 

 conditions, the rate of absorption is proportional to the difference of 

 the osmotic pressure of the blood and of the external medium, in so 

 far as the osmotic pressure of the blood is higher than that of the 

 outside medium. 



Hypophysis in Amblystoma.§ — J. S. Kingsley and F. W. Thyng 

 conclude that there is nothing in the history of the hypophysis in 

 Amblystoma to support the " palseostoma theory " of von Kupffer. It 

 arises as a paired structure ; it does not present gill-slit features, for it 

 comes into relation not with entodermal structures but rather with the 

 infundibulum. The paired condition, and the fact that columnar cells 

 are recognised in the early stages, imply that it was originally either 

 glandular or sensory. The tubular connection by which it long remains 

 in connection with the exterior (hypophysial stalk) may be interpreted 

 either as a duct for the paired gland, or as a tube to convey water to 

 the sense-organ at its extremity ; the tube lengthening to accommodate 

 the removal of the organ from the exterior caused by the cephalic 

 flexure. 



Abnormalities in Urodela.|| — G-. M. Winslow describes three cases : 

 Amblystoma punctatum, with bifid toe ; Plethodon ylutinosus, with bifid 



* Proc. Acad. Nat. Sci. Philadelphia, 1904, pp. 447-63. 



t Biol. Bull, v. (1903) pp. 2G1-70 (7 figs.). 



% Verh. Phys. Med. Ges. Wiirzburg, xxxvi. (1904) pp. 277-95. 



§ Tufts College Studies, No. 8 (1904) pp. 363-78. 



|| Tom.cit., pp. 387-410 (2 pis.). 



