88 Bashford Dean Memorial Volume 



female, with no indications whatever of any elements of the opposite sex in the genital 

 fold. As a result of our observations on the structure of the sex organ in both males and 

 females, therefore, it is quite evident that Bdellostoma hurgeri and Bdellostoyna stouti 

 are very rarely, if ever, hermaphrodite, either in the young or in the adult condition. As 

 Dean suggested (1899, p. 228), it is, therefore, quite improbable that the closely related 

 Myxine is functionally hermaphrodite; the extensive observations of the Schreiners seem 

 to have established this negative. That the sex organ in Myxine is frequently herma- 

 phroditic in structure there can be no doubt. All the European investigators have ob' 

 served that in the case of Myxine true males are very rarely found, true females are often 

 caught, but the preponderant majority of specimens taken are morphologically herma- 

 phrodites. This difference in the frequency of occurrence of hermaphroditism in Myxine 

 and Bdellostoma indicates that the genital organ of the former has proceeded in sex 

 specialization to a lesser degree than that of the latter. As suggested by the Schreiners, 

 the ancestors of the Myxinoidea may have been hermaphrodite; if so, Myxine is more 

 primitive than Bdellostoma in the structure of the genital organ. 



DEVELOPMENT TO MATURITY 

 OF THE EGGS OF BDELLOSTOMA 



Although several investigators have studied the structure and formation of the 

 membranes which surround each egg during the time when it is developing in the ovary, 

 no one has recorded any observations pertaining to the development of the eggs themselves. 

 That Dean's interest was aroused by certain phenomena related to the growth of the eggs 

 is attested by certain data which he recorded and some of the drawings which he made. 

 He made no descriptive notes in regard to this subject, however, and his ideas can only be 

 surmised from studying the tables and drawings. 



One striking fact that I observed in 1917 (p- 122), and also while examining hundreds 

 of specimens of Bdellostoma stouti at Pacific Grove in the summer of 1930, was that in 

 almost every female with large eggs in the ovary, the eggs next smaller in si2;e measured 

 about 1.5 to 2 mm. in length, with no intermediate sizes between them and the largest 

 eggs. All the latter were almost always within from one to three millimeters of being 

 uniform in size. It is quite probable that Dean also observed this fact in 1900. In Table 

 II, which he compiled from the data recorded in his small notebook, there is a column 

 marked "Percentage of females with eggs of nearly uniform size.'' Under ''Remarks" 

 for the first entry in this table are written the words : "After the large eggs — uniform — 

 comes next size, 3 mm. long." In the last two columns in the table are shown the number 

 and length of eggs in the specimens which have eggs of nearly uniform size. When the 

 figures in these last two columns are inspected in connection with the notations opposite 

 them under the heading "Remarks," it becomes evident that Dean very probably made in 

 1900 the observation which I made independently in 1917 and again in 1930. 



