On new Fishes from the Upper Congo. 309 



A certain number of parthenogenetic females become herma- 

 phrodites bj the production of sperm in parts of the ovaries. 

 It is possible that their transformation may continue until 

 in some cases, the developing eggs being completely resorbed, 

 the whole gland becomes a testis, and adult males are thus 

 rapidly produced. At the same time, it is more probable 

 that the true males are developed, under the influence of the 

 same unfavourable conditions, out of younger specimens not 

 yet sexually ripe. 



The whole subject of hermaphroditism in the animal 

 kingdom is one of vast interest and deserves a special study. 

 The Apodidse promise to yield useful results, inasmuch 

 as they could be experimented upon as Kurz (loc. cit.) experi- 

 mented with Cladocera. Indeed, the experiments of Kurz 

 with Cladocera might themselves be profitably repeated, 

 and individual specimens be carefully examined by the most 

 recent methods of fixing and staining. Much welcome light 

 might be thrown in this way upon the whole subject. In the 

 meantime, in view of the fact that the majority of Apodidse 

 which come into the hands of students are parthenogenetic 

 females and that the hermaphrodite specimens here described 

 are as yet unique, Professor Howes has kindly consented to 

 my depositing the slides in the Huxley Research Laboratory 

 at the Royal College of Science, South Kensington, where 

 they can be examined by any one interested in the subject. 



EXPLANATION OF PLATES XL & XII. 



[The detailed explanation of the figures will be found in the text.] 



Figs. 1, 2. The sperm-forming portion of the genital gland of Lepidurus 



glacialis, var. spitzbergensis (see pp. 298-299). 

 Figs. 3, 4. Ditto of Lepidurus glacialis (see pp. 299-300). 

 Figs. 5, 5 a. Sperm-formation in the genital gland of a specimen of 



Lepidurus productus (see pp. 300-301). 

 Fig. 5 b. Portion of duct of same. 

 Figs. 6-10. Sperm-formation in a specimen of Apus cancriformis (see 



pp. 301-303). 



XLI. — Descriptions of new Fishes from the Upper Congo. 

 By G. A. Boulenger, F.R.S. 



The new fishes here described were contained in a small 

 collection made some 50 miles south of Mangala by Mr. J. H. 

 Weeks and presented by him to the British Museum. The 

 known species are the following : — Hemichromis fasciatus y 

 Ann. & Mag. N. Hist. Ser. 6. Vol, xvii. 22 



