1 48 General Notes. [February, 



it differs from it in having the chorda dorsalis derived from the 

 mesoderm, and not from the endoderm. There is no real differ- 

 ence in the mesodermal layer of these two forms, and intermediate 

 stages between the two conditions have been observed in Elas- 

 mobranchs. So, also, the author thinks that the segmentation of 

 the ovum presents a transitional arrangement between the bony 

 fishes and Plagiostomes on the one hand, and the Cyclostomata 

 and Amphibia on the other. 



Zoological Notes. — The view that the Brachiopods are shelled 

 worms, which has been so fully discussed and insisted upon by 

 Professor E. S. Morse, appears to be gaining ground. Drs. O. and 

 R. Hertwig in their lengthy essay on the coelom theory agree 

 with Gegenbaur that the Brachiopods have little more in com- 

 mon with the molluscs than the possession of a shell, the latter 

 being wholly different from that of ordinary bivalves, and that 

 they have taken their origin from the stem of the worms, especial- 

 ly the Chaetopods. It appears that two shells from Lake Tan- 

 ganyika, in Central Africa, described in the Proceedings of the 

 Zoological Society of London, and, according to a note by Dr. C. 

 A. White in Nature, generically identical with the Pyrgulifcra 

 humerosa of Meek, from the Laramie group, an extensive brack- 

 ish water formation in western North America ; these beds being 



transitional between the Mesozoic and Cenozoic series. In a 



paper recently read by M. Yung before the French Academy on 

 the influence of the nature of food on sexuality, he states that he 

 fed separate sets of tadpoles with fish, meat, coagulated albumen 

 of hen's eggs, yellow of eggs, and with a mixed diet. These ali- 

 ments do not appear to have had a very distinct influence on the 

 sex ; but along with M. Born's experiments, those of M. Yung 

 support the idea that a special diet afforded to young tadpoles 

 from the time of leaving the egg, favors the development of a 

 female genital gland. This is the reverse of that arrived at by 

 Hoffman, who found that deficiency of nourishment resulted in 

 the case of plants, in the production of an excess of males. In 

 a recent memoir entitled " Metagenesis und Hypogenesis von 

 Anrelia aurita," Professor Haeckel by keeping a number of speci- 

 mens in his aquarium, has observed certain phenomena in the 

 mode of reproduction, which deviate from those which usually 

 occur. Beside-." \\v//r^> or tin ordin; try development by alter- 

 nate generation, he observed a direct development which he calls 

 hypogenesis. This is effected by the gastrula developing directly 

 into an Ephyra ; the Scyphistoma and Strobila stages being sup- 

 pressed. It remains to be seen whether this abbreviated mode of 

 development occurs in a state of nature. Two large plates crowded 

 with figures of generous size render the meaning of the text very 

 clear. Indeed Haeckel's style is as clear and beautiful as his 

 drawings and we wish fie papers were as easy 



to read. A ! ') i r > ' \ > i \a in t ca^ it M< no is! in ! 



