GENERAL OUTLINES OF ICHTHYOLOGY. 23 



size of the parent fish, or the ultimate size attained by the 

 species. 



Artificial production by impregnating the eggs taken 

 from the female fish, with the milt taken from the male 

 is now extensively practised, especially at Huningue near 

 Strasbourg, Perth in Scotland, Galway in Ireland, and 

 Hampton on Thames, by the Angling-Preservation Society 

 of that river, and promises to become a most important 

 subject with reference to the re- stocking of our exhausted 

 salmon fisheries. Mr. Bucklancf, the first of English pisci- 

 culturists, has recently exhibited, in the window of the 

 " Field " newspaper office, a beautifully constructed appa- 

 ratus for the artificial hatching of eggs, in which, by the 

 use of glass boxes, the whole process has been clearly 

 observable. Large quantities of the ova, both of salmon 

 and trout, have been brought to maturity in this ingenious 

 contrivance. 



There are a few exceptions to the rule of fishes being 

 oviparous. Amongst the Sharks and Rays one or two 

 species are viviparous, and produce their young alive and 

 complete in all respects. In those fishes which belong to 

 the cartilaginous series, the sexual parts are more highly 

 organized and complicated in their structure than those 

 of bony fishes, resembling, in fact, the sexual organs in 

 reptiles. 



A few other fishes, again, such as the Dog-fish and some 

 of the Rays or Skates, bring forth their young enclosed in 

 horny cases, two examples of which are here introduced, 



