Genital System of the Myxinoidea 97 



esting, however, is the fact that during this time I did not find any females with corpora 

 lutea in the ovary; the presence of large corpora lutea is positive proof that mature eggs 

 had been recently deposited. Another very interesting fact is that, like Dean, I was 

 unable to catch any eels during the last week in August. I fished from June 18th to August 

 28th, and up to the last ten days was catching one hundred or more specimens every day; 

 then on the succeeding two or three days the number of eels caught decreased, and during 

 the last week none was taken, even though the lines were shifted to many different places. 

 I am entirely at loss to state any conclusion regarding the time of spawning, excepting that 

 it is not definitely known. 



THE PROBLEM OF THE DESCENT AND RELATIONSHIPS 

 OF THE MYXINOIDEA 



Dean was also greatly interested in the problem of the descent and relationships of 

 the myxinoids, and he discussed some phases of this question in his description of the 

 general embryology of Bdellostoma stouti (1899, pp. 222 and 272). In this paper he wrote 

 as follows: 



And one can, I believe, say justly that upon this question there is no uniformity of belief 

 even among the few specialists who at present deserve to be ranked as the most competent 

 judges. The critics will at the best agree in but the single proposition that the cyclostomes 

 are a degenerate group — but they all will disagree as to the limits of this degeneration. ... It 

 is clearly evident that before any definite conclusions can be reached in these matters a wide 

 range of data must yet be forthcoming. But on what side should this be sought? Will it be 

 obtained on the sides of the morphology of fossil and recent forms? Is this additional evi' 

 dence to be forthcoming on the side of development? 



It was Dean's belief that the developmental history of the myxinoids would be 

 of some value in solving these general problems. As to paleontology, he expressed the 

 opinion that the cyclostomes "are such unfavorable subjects for preservation that their 

 lack of occurrence as fossils is in no way remarkable : but that their remains may be found 

 and ultimately prove of the greatest value in general determination no one can gainsay." 

 Subsequent investigations in the realms of morphology, embryology and paleontology 

 have demonstrated the correctness of Dean's predictions. 



The contributions from' embryology toward solving the problem of the descent and 

 relationships of the Myxinoidea have been confined to studies of embryos of Bdellostoma 

 stouti alone, for the embryos of no other myxinoid have been found. Possibly Dean sue 

 ceeded in collecting a few embryos of Bdellostoyna hurgeri in Japan in 1900 and 1901; 

 at any rate he made the following entry in his small notebook. This is the only reference 

 in his notebooks as to obtaining eggs of Bdellostoma hurgeri. 



Eggs from boat for Kuma [head fisherman and collector at Misaki]. From slime of a 

 lump from several individuals — all together — gather animals just as in Cal." 



