ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 23 



Orbital Glands of White Rat.* — Prof. N. Loewenthal finds that in 

 addition to the infraorbital, there is in the white rat auother gland which 

 has a connection with the orbital cavity. This new gland lie calls the 

 glans orbitalis externa. It lies beside the parotid, but nevertheless opens 

 with the intraorbital by a common duct in the vicinity of the external 

 angle of the eye. 



Variation in Vertebral Column in Man.f — C. E. Bardeen notes that 

 the vertebral column and ribs in man show frequent deviation from the 

 normal. In fifty-nine cases, thirty only were perfectly normal as 

 regards these structures. The commonest variation is the reduction of 

 the twelfth rib to the rudimentary condition, and this, and other more pro- 

 nounced illustrations of a tendency towards the shortening of the verte- 

 bral column, occurred in twenty-three cases. In six cases the vertebral 

 column showed a tendency to lengthen, and in two of these there were 

 thirteen rib-bearing vertebras. 



Integument of Erethizon dorsalis.J — Dr. Theodor Loweg concludes, 

 from a study of the skin of foetus and adult of this rodent, that its 

 ancestors must have been covered with scales, and that the character- 

 istic bristles and spines developed beneath the posterior free border of 

 these scales. The arrangement of the spines shows that the scales were 

 the primitive structures to which the spines have adapted themselves. 

 Further, in the foetus the skin is marked by warts and quadrilatera 

 areas which are to be regarded as the last remnants of the ancestra 

 scales, and are most developed on the dorsal surface. The fine soft 

 hairs which in the adult fill up the gaps between the spines develope late, 

 are quite irregularly arranged as contrasted with the regular spines, and 

 occupy the spaces left by the disappearing scales. Sweat-glands are 

 absent, and the author regards it as not improbable that the luxuriant 

 growth of soft hair is lost in the summer-time. The structure of the 

 spines and bristles is described in detail. The true spines have dark 

 strongly barbed tips, while barbs are at best only slightly developed on 

 the bristles. Near the axilla, but towards the dorsal surface, there is at 

 either side of the body a conical skin-papilla surrounded by a furrow. 

 These papillae, in spite of the fact that they are small and lie among 

 the bristles, the author believes to be the teats, which, according to 

 Brehm, the North American Indians declare to be absent. The author 

 believes that during the lactation period they become turgid and elon- 

 gated, so that they can be reached by the young. Their position is per- 

 haps due to the fact that the animals are climbers, and the mother would 

 be more hampered in the act of climbing if they were placed elsewhere. 

 The illustrations include a striking photograph of the foetus, showing the 

 arrangement of the foetal bristles. 



Variation in Didelphys virginiana.§— Mr. C. F. W. McClure finds 

 that opossums from the neighbourhood of Princeton show an extra- 

 ordinary range of variation in regard to the venous system. He describes 

 in detail the variations in regard to the posterior tributaries of the vena 

 cava posterior of twenty-six specimens. The details are outside our 



* Arch. Mikr. Anat., lvi. (1900) pp. 535-52 (1 pi.). 



t Anat. Anzeig., xviii. (1900) pp. 377-82. 



t Jen. Zeitschr. Naturwiss., xxxiv. (1900) pp. 833-GG (2 pis.). 



§ Anat, Anzeig., xviii. (1900) pp. 441-60 (21 figs.). 



