62 AMERICAN FISHERIES SOCIETY. 



fresh water is carried into the case to aerate the embryo and fa- 

 vor its incubation. This peculiar egg case is formed in the end 

 of the oviduct, which is different from the egg membrane oc- 

 curring in any of the true bony or Teleost fishes, since it is 

 formed of horizontally interwoven fibres. The egg case of the 

 cestracion, or Port Jackson shark, is formed in the same way, 

 but instead of being- flat and quadrangular, is twisted into a spiral. 

 I am not positive, however, that the eggs of the Port Jackson 

 shark are suspended. Another type is found in the Scomhere- 

 socidcE, in which the entire egg membrane is covered with strong 

 filaments, which wind round each other and intertwine with the 

 similar filaments of contiguous eggs, which are consequently, 

 held together and suspended, sometimes in masses several inches 

 in length, such masses being commonly found in great numbers 

 hanging to the meshes of pound nets during July and August. 

 The egg itself measures one-eighth of an inch in diameter. 

 There is another somewhat similar type in which the egg is very 

 much smaller. This is the egg of one of the commonest fishes 

 found in the waters tributary to the Chesapeake bay, viz., Menidia, 

 one of the Antherinidcz. They are provided with four filaments, 

 attached to one side of the ^gg, by which they are in like manner 

 suspended and held together in strings. Again, there are still 

 other types in which the ova are hatched in the mouth, as in the 

 case of AruncB, or marine catfishes. Their eggs are very few in 

 number, but they are as large as those of a robin. Some of the 

 smaller blennies take advantage of a dead oyster shell in which 

 to conceal and deposit their adherent eggs. 



There are yet other cases in which the male builds a nest. One 

 of the most extraordinary instances of this kind is the common 

 four spine stickleback {Apeltes), which I described four years 

 ago. The male, which is much smaller than the female, has a 

 pouch on the right side of the rectum, from which is poured out 

 a viscid secretion, and which is spun out into threads fitfully by 

 the animal, as he goes around a bunch of water weeds like a 

 bobbin to build a little basket-like nest for the eggs. After he 

 has induced the female to oviposit, he tends the eggs very 

 faithfully until they hatch. Some investigators go so far as to 

 say that after the eggs are hatched, the male stickleback will 



