ZOOLOG-Y AND BOTANY, MICKOSCOPY, ETC. 221 



Unicellular Glands in the Cloaca of Rays.* — J. H. List records 

 the presence of goblet cells conspicuous by their size among the 

 epithelial cells of the cloaca in Torpedo marmorata and Bay a miraletus; 

 they occur even in the deepest layers, and are independent formations 

 serving as unicellular glands. 



Intercellular Spaces and Bridges in Epithelium.t — P. Mitro- 

 phanow, from a study of the integument in Axolotl and Triton, both in 

 the embryonic and adult stages,.and from other investigations, concludes 

 that the cells of the deeper epithelial layers are connected with one 

 another by bridges which are shown by development to arise from the 

 protoplasm of growing cells. These bridges consist of a living pro- 

 toplasm since they are parts of the substance of the cell ; they are 

 capable of elongation during the widening of the intercellular spaces 

 under the pressure of a quantity of fluid, and they are also able to 

 shorten; when the latte- happens the cells may come to touch one 

 another, and the lacunae disappear altogether. The intercellular spaces 

 form a complicated network of intercommunicating canals which stand 

 in direct relation to the lymphatic vessels ; they are during life more 

 or less filled with lymph, which, in special circumstances, separates the 

 epithelial cells from one another and gives abnormal dimensions to 

 the spaces. The existence of these lacuna explains the presence 

 of the so-called wandering cells in the epithelium, the passage of 

 pigment-cells, and the mode of entrance and termination of the nerves 

 in the epithelium. And, further, they are of importance for their 

 bearing on the theory of the uninterrupted structure of the animal 

 organism. 



Size of the Surfaces of Organs of riight.| — This forms the 

 subject of a series of elaborate measurements by K. Miillenhoff. After 

 giving an account of earlier investigations, beginning with those of De 

 Lucy in 1865, he gives his own tabular statement of the results derived 

 from measurements, &c., of the relations between body-weight and 

 wing-surface, with a full account of the methods employed, and a 

 classification of flying creatures (birds, insects, and others) according 

 to the size of their organs of flight, and some calculations respecting 

 rapidity of wing-strokes. 



Phylogenetic Classification of Animals.§ — W. A. Herdman has 

 published a phylogenetic classification of animals for the use of 

 students, in which considerable attention is directed to those hypo- 

 thetical ancestral forms which are rarely mentioned in text-books. 

 We note that Prof. Herdman still retains the group Mesozoa, and 

 looks on them as being degenerated descendants of Gastrcea ; the 

 Ctenophora are regarded as leaving the hydroid stock at the same 

 point as the Gymnoblastea and Hydrocorallina. The Crinoidea 

 stand at the apex of the Echinoderm phylum, which starts from the 

 prime axis above the Platyelmia together with the chordate stock 



* Zool. Anzeig., viii. (1885) pp. 50-51. 

 t Zeitschr. f. Wiss. Zool., xli. (1884) pp. 302-9 (4 figs.), 

 t Pfliiger's Arch. f. d. Gesammt. Physiol., xxxv. (1884) pp. 407-53. 

 § Herdman, W. A., 'A Phylogenetic Classification of Animals,' iv. and 76 pp. 

 (20 figs and 1 table), 8vo, London and Liverpool, 1885. 



