Genital System of the Myxinoidea 87 



into the body cavity, each suspended by a narrow strand of rnesovarium. The large eggs 

 in this specimen are not very numerous; some were probably lost while the eel was being 

 handled. 



In the next older female selected by Dean to illustrate the development of the ova 

 (Figure 12), the eggs are from 11 to 13 mm. in length, but are much larger than the largest 

 in the specimen shown in Figure 11; the increase in growth has been more in circumfer- 

 ence than in length. The ends are not as pointed as they are in younger eggs. The in- 

 creased weight of the eggs has stretched the mesovarium in the vicinity of each egg into a 

 longer strand. 



A female with older eggs is shown in Figure 13, plate III. The largest of these 

 eggs are from 15 to 18 mm. long, and they are likewise larger in the transverse diameter 

 than those shown in Figure 12. A female with eggs that are almost ready to be deposited 

 is shown in Figure 14, plate IV. The eggs are from 20 to 22 mm. long, and 7 to 8 mm. 

 wide. The largest eggs recorded by Dean were 29 mm. long by 9 mm. wide. The aver- 

 age length of seventy eggs was 22.8 mm. The mesovarium in females containing eggs 

 almost ripe is very broad, and is stretched into long, narrow, twisted strands at the places 

 where the large eggs are attached. Sometimes adjacent strands of the mesovarium become 

 ■ tangled together, and may even be tied in loose knots. A female containing large eggs 

 usually has from 25 to 45 or more, and their contours can easily be seen from the exterior. 

 The mass of the numerous mature eggs causes the body cavity to be slightly enlarged by 

 expansion of its walls. Neither Dean nor I succeeded in catching any females with eggs 

 lying in the body cavity, free from the ruptured ovarian capsules, ready to be deposited. 

 European investigators likewise record that they have been unable to get any females of 

 Myxme containing fully mature eggs. It has been suggested by some authors that the 

 females do not eat during the time they are ready to deposit eggs, consequently cannot be 

 taken on hooks or in traps. Dean suggested that possibly they hide under rocks or in 

 holes at this time. From my experience in collecting naturally deposited eggs, I believe 

 this is probable. 



Nowhere in his notes does Dean make any mention of having observed testicular 

 tissue in the ovary of any female. None of his drawings shows a female individual having 

 a testis anywhere in the sex organ. It is reasonable to infer, therefore, that he did not 

 find any female specimen whose sex organ contained any male sex elements. Among all 

 the females of Bdellostoma stouti which I examined in the summer of 1930 there was not 

 one which -had any testicular tissue in the posterior part, or in any other part of the mes' 

 ovarium. In its posterior two or three centimeters the mesovarium was usually entirely 

 without any sex elements, but occasionally it contained a few quite small eggs. 



In Bdellostoma hurgeri and B. stouti, then, both Dean and I found the sex organ in 

 each individual hagfish examined, excepting one (Dean's specimen No. 393), to be distinctly 

 either a testis or an ovary; that is, each individual hagfish was either a true male or a true 



