96 Bashford Dean Memorial Volume 



Very significant also, in respect to the breeding season, are the data in Dean's note- 

 books regarding the males caught in the different months of the year. These data are 

 shown by Dean in condensed form in Table II (page 81) and in this graph. During the 

 months immediately preceding the breeding season, when the eggs in females were ap- 

 proaching the size and condition of maturity, a very large percentage of the eels caught 

 were males, as can be seen in Table II (page 81). On July 18th the males constituted 

 62 per cent of the total catch; on July 25th, 78 per cent, and on August 29th, immediately 

 before the eels began breeding activities, 83 per cent were males. Under "Remarks" for 

 this date Dean wrote: "Many large males, average about 48 cm." Immediately after the 

 breeding season fewer males were taken, 13 per cent of the catch on October 28th and 24 

 per cent on October 30th. The notation under "Remarks" for the latter date states: 

 "All mature males spent." The proportion ot males increased to 37 per cent on Nov. 25th; 

 during the months from December to June, inclusive, while the eggs in the females were 

 developing, approximately equal numbers of males and females were taken in each 

 day's catch. These months may be a period of sexual quiescence. 



The conclusion which Dean drew from his observations, namely, that the spavining 

 season for Bdellostoma is during late August, all of September, and the first three weeks 

 of October, is at variance with his statements in 1899 (p. 224) : 



I find, furthermore, that embryos can be obtained during the late fall and early winter, 

 in stages which enable me to extend the known season of ovulation throughout the entire 

 year. A time representing the optmium spawning probably occurs; and this I believe to be the 

 last of spring and the first month of summer, basing this view upon the uniform si2,e of embryos 

 collected during the months of August and September, and upon the growth rate of embryos 

 which I attempted to rear. 



It is possible that Dean changed his opinion regarding the time of spawning after 

 making observations on Bdellostoma hurgeri in 1900 and 1901. The two differing views 

 emphasi2;e the fact that the spawning time for the Myxinoidea is not yet known. 



My own experience has been too limited to be of assistance in solving this question. 

 Like other investigators, I have in every month of the year collected females of Mvxme 

 with large eggs which had the appearance of being almost ready to be extruded. But the 

 time required for the eggs to grow to the mature condition is not known; it is possible 

 that a female carries large eggs for almost a year before they are ready for depositing. 

 One cannot be positive, therefore, that the presence of large eggs in females taken in every 

 month means that there is no definite season for ovulation, and that eggs are deposited at 

 all times of the year. More significant, perhaps, than the presence of large eggs in females 

 at all seasons, is the condition of development of embryos recovered from the bottom of 

 the ocean in different months. During each of the months of June, July and August, 1930, 

 I collected embryos of Bdellostoma stouti in all stages of development from blastodermic 

 discs to embryos almost ready to hatch. This would indicate that spawning occurs before 

 and during those three months. On almost every day of this time I caught females repre- 

 senting all stages in the growth of the eggs, from the smallest to the largest. Very inter' 



