432 Wyman's Observations on 



Art. XXVI. — Observations on the Development of An ableps 

 Gronovii, (Cuv. &f Veil.) By Jeffries Wyman, M. D. 

 Read Sept. 20th, 1854. 



While the general plan of the development of Fishes and 

 Batrachian Reptiles conforms strictly to the an-allantoidian type, 

 the external conditions under which the process of the form- 

 ation of the embryo is carried on, vary to a very remarkable 

 degree. In the larger majority of instances, eggs are scattered 

 without care, or perhaps only a locality is selected which 

 furnishes the most favorable circumstances, in relation to cur- 

 rents of water, the kind of bottom, the exposure to light, &c. 

 Once deposited, they are no longer attended to. 



In other cases, but these are comparatively few, the fishes 

 construct something which serves to protect the eggs, and in a 

 measure answers the purpose of a nest ; in this the eggs are 

 laid and undergo their evolution. The Lamprey builds a rude 

 structure, consisting of a pile of stones brought from a dis- 

 tance, in the mouth ; both sexes cooperating in the labor of 

 building. The eggs are deposited between the stones as the 

 structure is reared, and remain there in security until hatched. 

 The Chub (Catostomus tuberculatus) has a similar habit. Our 

 common Bream {Pomotis vulgaris,) and a species of Gobius 

 found in the Mediterranean, (the Phycis of Aristotle,)* both 

 construct a true nest, composed of aquatic plants, in which 

 the ova are developed, one or the other of the parents stand- 

 ing guard as the embryo passes through its different stages. 

 But the most remarkable nests built by fishes, are those of the 

 "Hassars" (Collicthys) of Demarara, and of the "Stickle- 

 backs" (Gasterostei) of Europe. The "Round-headed Has- 

 sar" forms its nest of leaves, and the " Flat-headed Hassar " 

 of grass. Of the two species of Stickleback described by Coste,f 



* Owen. Lects. on Comp. Anat. Vol. II. p. 304. 



f Instructions Pratiques sur la Pisciculture, suivies de Memoires, et de Rap- 

 ports sur la meme sujet. Par M. Coste, Professeur au College de France. 

 Paris, 1853. 



