42 Umisual Modes of 



RivuLARi^, Hass. 



Raphidia viridis, Hass. Britisli Fresh-water Algae, p. 265, pi 

 64, fig. 3. In rock pools, Point des Monts. This 

 plant bears some resemblance to the Rivularia nitida 

 of Harvey's Man. p. 222 ; but although a salt-water 

 species it is yet more like the R. viridis of Hass. which 

 abounds in the fresh-water of the St. Lawrence. 



ARTICLE V. — Unusual modes of Gestation in Batradiians and 

 Fishes. 



[Prof. Wyman of Harvard has lately returned from an excur- 

 sion across North America, in the course of which he has collected 

 many curious facts in natural history ; among others, the follow- 

 ing, which we extract from a communication to the Boston Society 

 of Natural History.] 



" Among Batrachians the circumstances under which the young 

 are developed, though less varied than in some of the other classes 

 of vertebrates, still present a considerable range. By most species 

 the eggs are deposited in the water either upon aquatic plants or 

 on the bottoms ; by others, as in Salamandra eri/thronota, they 

 are laid in damp places under logs or stones ; with some the 

 evolution of the embryo commences a short time previous to the 

 laying of the egg and is completed subsequently, while there are 

 species which are wholly viviparous. 



"The most remarkable deviations from the ordinary modes are 

 to be found in those instances in which the eggs, after being laid,, 

 are ajrain brouo^ht into a more or less intimate relation with the 

 parent, as in the "Swamp toads " (^Pipa Americana^ of Guiana, 

 where each ovum is developed in a sac by itself on the back of 

 the female, in Notoddphys of Venezuela, where all the eggs are 

 lodged in one large sac, also on the back, and is analogous to the 

 pouch of the Marsupials, and in Alytes, the " Obstetric toad " of 

 Europe, where the eggs are wound in strings around the legs of 

 the male, who takes care of them until they hatch. • 



" The species, the habits of which are noticed below, and which, 

 in so far as I have been able to learn, have not attracted the 

 attention of naturalists, adds another to the series just mentioned, 



