236 FRESH FACTS [march 1899 



Monotremes," Quart. Journ. Micr. Sci. xli. 1899, pp. 549-588, 3 pis. and 6 

 figs. In all essential respects the development of the hairs in Monotremes is 

 precisely similar to that of other mammals ; the early development of the 

 follicle is in the form of a solid epidermic downgrowth, not tubular to start 

 with as Poulton described it. 



A Parasite of the Brain. Albert W. Brown. " On Tetracotyle petro- 

 myzontis, a Parasite of the Brain of Ammocoetes," Quart. Journ. Micr. Sci. 

 xli. 1899, pp. 489-498, 1 pi. The existence of so highly organised a form as a 

 Trematode in the brain cavity of a vertebrate is a unicme phenomenon in many 

 ways, and this must commend Tetracotyle petromyzontis to the interest of 

 naturalists. It is, the author says, almost incredible that any vertebrate could 

 live on, apparently without discomfort, whilst its brain is packed with hundreds 

 of flukes. But this is the case. 



More Experimental Embryology. Henry E. Crampton, Jr. "The 

 Ascidian Half-Embyro," Ann. Neio York Acad. Sci. x. 1898, pp. 50-57, 

 2 pis. An isolated blastomere of Molgula manhattensis segments as if still 

 forming a corresponding part of an entire embryo. The cleavage phenomena 

 are strictly partial ; the result is a larva of less than normal size, and with 

 defects in certain of its systems. Mr. Crampton's results confirm the view of 

 Roux, that the development begins as a partial one, but that the missing part 

 is gradually supplied by the cells already present, so that the partial nature of 

 the development is progressively masked, and the end is a nearly complete 

 larva. 



Intercellular Bridges. Hermann Klaatsch. "Die Intercellular- 

 structuren an der Keimblase des Amphioxus," SB. Akad. Wiss. Berlin, 1898, 

 pp. 800-806, 4 figs. There is a well-developed system of intercellular connec- 

 tions persistent to the end of the gastrulation process, if not longer. Ectodermic 

 cells are connected, and endodermic cells are connected, but there is no connec- 

 tion between ectoderm and endoderm except at the transitional zone. 



New Case of Parental Care in Frogs. August Brauer. " Em neuer 

 Fall von Brutpflege bei Froschen," Zool. Jahrb. xii. 1898, pp. 89-94, 3 figs. 

 Dr. Brauer found in the Seychelles a small frog (Arthrolejrtis seychellensis) which 

 bore on its (his X) back nine tadpoles fixed by their ventral surface. 



Two New British Mammals. — At a meeting of the Zoological Society of 

 London on February 7, Mr. G. E. H. Barrett-Hamilton, F.Z.S., read a paper 

 on the Mice of St. Kilda, of which he recognised two species — Mus hirtensis 

 sp. nov., a representative of M. sylvaticus, and M. muralis sp. nov., representing 

 M. musculus. Both of these species showed good distinctive characters from 

 their well-known prototypes. 



