84 Bashford Dean hiemorial Volume 



bears the dates 1900 and 1901, and at the top of the table is written "H. burgeri," crossed 

 with two lines. This leads me to think that the drawings illustrate specimens of Bdellos^ 

 toma hurgeri. I know by comparison, however, that corresponding specimens of Bdellos- 

 toma stouti present exactly the same appearances as shown in the drawings, and therefore 

 the latter might well illustrate either of these two species of hagfish. 



In all the males represented in the drawings the testis is confined to the posterior 

 one-fifth or less of the mesorchium. The gonad in the youngest male illustrated (Figure 1, 

 plate I) shows very little differentiation. In this specimen the mesorchium is narrowest 

 at the anterior and posterior ends where it is merely a ridge along the mesentery; it is 

 widest in the central part. The testis is indicated by a slight thickening along the free 

 (outer) margin of the mesorchium in its posterior part. A slightly older stage of develop' 

 ment is shown in Figure 2. The mesorchium is wider than in the preceding specimen, and 

 is slightly waved in its posterior part. In the specimen illustrated in Figure 3 the waved 

 condition in the posterior portion of the mesorchium is increased, and a definite band can 

 be seen in its free margin. This band consists of numerous small follicles closely packed 

 together, giving the free margin of the mesorchium a beaded appearance. This is now the 

 widest part of the mesorchium; the anterior portion has not increased in width, and con' 

 tains no sex elements whatever. 



The testis in the specimen illustrated in Figure 4 is considerably more advanced in 

 development. The posterior part of the testis band is quite thick and is thrown into short, 

 deep folds, indicating increased growth in a limited area. The anterior portion of the 

 mesorchium shows no change over the condition in the last specimen, and contains no sex 

 elements. 



The adult appearance of the male gonad is illustrated in Figure 5. The testis occupies 

 the posterior oncfourth of the mesorchium; the anterior portion of the latter is wider 

 than it is in the preceding specimens, and is entirely free of sex elements. The testis has 

 increased in width and in thickness, and is considerably more lobulated and folded. 



All the specimens illustrated in Figures 1 to 5 are true males, with no trace of e^gs 

 anywhere in the genital fold. As stated above, Dean recorded only one specimen which 

 had both ova and testicular tissue in the genital fold, and this he interpreted to be a young 

 male, 34 cm. long, ""with young eggs." 



Among the many specimens of Bdellostoma stouti which I examined in 1930, I found 

 no male individuals in which there were any indications of eggs anywhere in the mes' 

 orchium. In some of the males there were scattered testicular follicles in the anterior 

 portion of the mesorchium, and in a very few specimens a narrow band of testicular tissue 

 extended along the entire length of the mesorchium from the gall bladder to the caudal 

 end of the body cavity. I carefully examined the testis in numerous males while they 

 were still living, and was impressed by the scantiness of the spermatic fluid in the gonads. 

 Microscopic examinations revealed myriads of active spermato2;oa in the spermatic fluid, 



