( 247 ) 



XI. — The Reproductive Organs of Bdellostoma, and a Teleostean Ovum 

 from the West Coast of Africa. By J. T. Cunningham, B.A. 



(Read 5th July 1886.) 



During a short visit I paid to Oxford in the month of June last I had the 

 opportunity of examining, by the kind permission of Professor Moseley, a 

 number of specimens of Bdellostoma Forsteri, which were some of a large 

 number brought from the Cape by Mr Adam Sedgwick of Trinity College, 

 Cambridge. This examination showed what, from the close affinity of the two 

 forms, was naturally to be expected, namely, that the structure of the repro- 

 ductive system and the development of the reproductive elements in Bdel- 

 lostoma were very closely similar to the structure and development of the 

 corresponding parts in Myxine. A short time ago I described before the 

 Society some ovarian eggs of Myxine, obtained at the beginning of the present 

 year, which were approaching maturity. In these eggs there were slight pro- 

 jections at the poles, and on the surface of the projecting parts a number of 

 papillae. The projections were caused by the growth of a number of threads 

 from the vitelline membrane within the ovarian capsule, and the papillae were 

 the separate elevations produced by the threads. In one of the specimens of 

 Bdellostoma which I examined at Oxford there were a number of ovarian eggs 

 in an exactly similar condition. These eggs of Bdellostoma are of course much 

 larger than those of Myxine ; the eggs of the latter, in the condition I refer to, 

 were 21 cm., those of the former are 35 cm. No one has seen the perfectly 

 ripe eggs of Bdellostoma after their escape from the ovary, but the specimens 

 I have described prove conclusively that the eggs of this species when shed are 

 provided with a number of polar threads, which are processes of the vitelline 

 membrane, exactly as in Myxine. I have not yet made a microscopic 

 examination of the reproductive organs in Bdellostoma, but from what I could 

 see by ordinary dissection, it is evident that all the peculiarities which exist in 

 the reproductive system in Myxine occur also in Bdellostoma. A number of 

 specimens possessed sexual organs, in the anterior part of which were minute 

 ova, while the posterior part was evidently testicular tissue; and in one or two 

 other specimens the whole organ seemed to be testicular. The small quantity 

 of testicular tissue in a given specimen was also noticeable, as in Myxine. I 

 found no specimens which showed indications of having recently discharged 

 their eggs. I have ascertained from Mr Sedgwick that his specimens were 

 collected in August and September, and this fact shows that the breeding period 



VOL. XXXIII. PART T. 2 N 



