424 SUMMARY OF CURRENT RESEARCHES RELATING TO 



animals, and there are special chapters on adaptation to circumstances, 

 man, and zoological work. For a little book of this sort there seem to 

 us to be too many technicalities, but the authoress has not taken her 

 work lightly and deserves congratulation for successfully avoiding the 

 misleading suggestion of false simplicity. The illustrations are not up 

 to the level of the text. 



Variations in Vascular System of Rana temporaria.*— E. Warren 

 has noticed in four years five cases (out of about 200) in which a blood- 

 vessel connected the apex of one of the lungs with the rectal vein of the 

 hepatic portal. He refers to other striking abnormalities, and asks 

 Continental workers to notice if similar variations occur in Rana 

 escalenta. 



Variations in Human Vertebral Column.f — P. Ancel and L. 

 Sencert discuss the numerical variations in the human vertebral column, 

 propose four categories embracing the recorded variations, and discuss 

 the possible interpretations. 



The most frequent variations are of a compensatory character, due 

 to accommodation, others are referable to difficulties connected with the 

 movements of the pelvis ; a few, notably cervical, imply some change in 

 the primitive segmentation. 



There is an evident relation between the appearance of cervical ribs 

 and the reduction of the number of pre-sacral vertebrae ; but which 

 change is primary remains obscure. 



Variation in Snakes.} — E. C. Eckel, in a systematic catalogue of 

 the snakes of the north-eastern United States, Las a few notes on varia- 

 tion. Notable examples are the common garter snake (JEutsenia sirtalia) 

 and the milk snake (Osceola doliata). In regard to melanism, it is noted 

 that in Heterodon platyrhinus the black coloration Las no systematic im- 

 portance, while in Natrix fasciata sipedon it seems that the darker color- 

 ation in New York and New England specimens is general and not 

 merely individual in its occurrence. 



Teeth of Hag and Lamprey.§ — E. Warren has made sections 

 through young forms, and does not confirm the conclusion of Dr. Beard 

 that the teeth show odontoblasts. The cone of " odontoblasts " is purely 

 epidermal in origin, and is, in fact, a successional tooth developing 

 beneath the functional tooth. 



The structure of the teeth does not lend support to the idea that they 

 are degenerate derivatives of calcified teeth. If they actually are 

 degenerate they must be regarded as having reverted to a condition that 

 probably preceded the placoid scale of an Elasmobranch — a horny wart 

 with a pulp-cavity 



Excretory Organs of Amphioxus.|| — E. S. Goodrich adds a little to 

 the preliminary paper in which he pointed out that in their segmental 

 arrangement, in their function, and in their histological structure, the 

 excretory organs of Amphioxus and the nephridia of Phyllodoce are in all 

 essentials identical. 



* Zool. Anzeig., xxv. (1902) pp. 221-2. 



t Joum. de l'Anat. Physiol., xxxviii. (1902) pp. 217-58 (2 pis.). 



X Bull. New York State Museum, li. (1902) pp. 356-88 (24 figs.). 



§ Quart. Joum. Micr. Sci., xlv. (1902) pp. 631-6 (1 pi.). 



|| Tom. cit., pp. 493-501 (1 pi. and 1 fig.). 



