57-2 



ANATOMY OF VERTEBRATES. 



383 



most Osseous Fishes the ovaria, fig. 383, a, form two elongated 

 sacs of mucous membrane, with a tliin fibrous tunic and a perito- 

 neal covering, closed anteriorly, but produced posteriorly into a 

 short, straight, and commonly wide oviduct, terminating behind 

 the anus, and commonly before the urethra, fig. 281, i. In the 



Pipe-fishes the oviducts con- 

 tinue distinct to the cloaca. 

 In most Fishes the oviducts 

 coalesce, after a brief course, 

 as in the Herring, or after a 

 longer course, into a single 

 tube before arriving at the 

 cloaca : the common terminal 

 portion becomes much dilated 

 in the Cod-fish, the Lump-fish, 

 and- some others. The ' stroma,' 

 or cellular tissue, which is the 

 seat of developement of the 

 ova, is interposed between the 

 mucous and fibrous tunics of 

 the ovarian sac : it sometimes, 

 though rarely, is coextensive 

 with the mucous membrane. 

 In the Lophius the two ovaria 

 are long and large plicated 

 tubes, flattened when empty, 

 cylindrical when inflated, with 

 the ovigerous stroma lining, as 

 it were, only the ventral half 

 of the walls of the cylinder, and terminating where the oviducal 

 portions of each sac unite together to form the common short 

 efferent canal. The inner surface of the ' stroma ' is beset with 

 small tubercles, arranged in interrupted linear series, each tubercle 

 supporting four or five papilliform ovisacs. In the Pike the stroma 

 forms a longitudinal strip, in short transverse plaits, along the 

 median side of the long ovarian sacs: fig. 383, B, shows two of the 

 ovarian plaits, from which the developed ova hang in subpediui- 

 cidate ovisacs. In the Wolf-fish the stroma extends over the 

 whole of the internal surface of the ovary, into the cavity oi 

 which it projects in the form of numerous oval compressed 

 processes. In general, its superficies is extended by being plaited 

 into numerous folds, which are transverse in the Cod and Salmon, 

 oblique in the Mackerel, and longitudinal in some other Fishes. 



Ovarlea and oviduct of an Osseous Fish. 



