824 STRUCTURE AND DEVELOPMENT OF LEPIDOSTEUS. 



which he has arrived, or to necessitate any modification in the 

 views on this subject expressed by one of us l . 



The genital ducts of Ganoids and Teleostei have for some 

 time been a source of great difficulty to morphologists ; and any 

 contributions with reference to the ontogeny of these structures 

 are of interest. 



The essential point which we have made out is that the ante- 

 rior part of the oviduct of Lepidosteus arises by a fold of the 

 peritoneum attaching itself to the free edge of the genital ridge. 

 We have not, unfortunately, had specimens old enough to decide 

 how the posterior part of the oviduct is formed ; and although 

 in the absence of such stages it would be rash in the extreme to 

 speak with confidence as to the nature of this part of the duct, it 

 may be well to consider the possibilities of the case in relation 

 to other Ganoids and Teleostei. 



The simplest supposition would be that the posterior part of 

 the genital duct had the same origin as the anterior, i. e., that it 

 was formed for its whole length by the concrescence of a peri- 

 toneal fold with the genital ridge, and that the duct so formed 

 opened into the segmental duct. 



The other possible supposition is that a true Miillerian duct 

 i.e., a product of the splitting of the segmental duct is sub- 

 sequently developed, and that the open end of this duct coalesces 

 with the duct which has already begun to be formed in our 

 oldest larva. 



In attempting to estimate the relative probability of these 

 two views, one important element is the relation of the oviducts 

 of Lepidosteus to those of other Ganoids. 



In all other Ganoids (vide Hyrtl, No. 1 1) there are stated to 

 be genital ducts in both sexes which are provided at their ante- 

 rior extremities with a funnel-shaped mouth open to the abdo- 

 minal cavity. At first sight, therefore, it might be supposed 

 that they had no morphological relationship with the oviducts 

 of Lepidosteus, but, apart from the presence of a funnel-shaped 

 mouth, the oviducts of Lepidosteus are very similar to those of 

 Chondrostean Ganoids, being thin-walled tubes opening on a 

 projecting papilla into the dilated kidney ducts (horns of the 



1 F. M. Balfour, Comparative Embryology, Vol. n., pp. 600 603 [the original 

 edition]. 



