MORPHOLOGY OF CYPRINODONT FISHES. 



11 



The vas deferens has a thin wall, comprising an outer fibrous 

 layer and an inner layer of mucus-secreting cells ; within the 

 testis the tubules that unite to form the vas deferens have a similar 

 structure (PI. IV. C). The epidermis of the glandular groove also 

 secretes mucus, and in the neighbourhood of the seminal papilla 

 and on the papilla itself the area of secreting-cells is increased 

 by folding. 



Text-fie"ure 7. 



Neostethus lankesteri, $. Transverse sections (X 18) : A, passing through the 

 posterior part of the seminal papilla, and B, through the priapium near^its 

 posterior end. 



Ic., kidney; I., liver; s., stomach ; i., intestine; v.d., vas deferens ; u., ureter; 

 a., axial bone; p., papillarj' bone; ct., ctenactinium, e., efferent groove. 



The tubules of the testis, the vas deferens, and the glandular 

 groove in the neighbourhood of the seminal papilla hold a mucus 

 secretion, in which appear numerous spermatophores ; these are 



