134 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1885. 



the body of the foetus at a very early period becomes covered with scales, 

 absorption could only take place through the intestinal canal or by the 

 surface of the yelk-sac, which invests the viscera and increases in size 

 for a long period after the yelk itself has wholly disappeared. In the 

 later stages of gestation even the yelk-sac is out of the question, since 

 it in turn wholly disappears, while the foetus occupies the general cav- 

 ity of the ovary." 



Great interest attaches to the peculiar development of the rows of 

 papill* on the empty yelk-bag of AnabJeps as described above by Wy- 

 man. Its continued growth with the growth of the foetus up to a cer- 

 tain stage of advancement is also remarkable ; in fact, so far as yet 

 known, it is unique amongst osseous fishes. The peculiar character of 

 the villi on the yelk-bag remind one somewhat of what has been ob- 

 served by Osborn in the structure of yelk sac of the uterine fcetus of 

 DideJphys, and by Owen in Macropus, in which the foetal membranes 

 fitted into uterine furrows, but were not adherent to the uterus and 

 without villi. This structure in Anableps also reminds one of the hol- 

 low villi developed in certain mammalian blastodermic vesicles de- 

 scribed by Bischoff. It is therefore unfortunate that Professor Wyraan 

 was not in a position to describe the minute histological structure of 

 this abdominal sac in the foetus of Anahleps more fully, so that a more 

 exact comparison could have been instituted between jt and the yelk- 

 bag or inferior pole of the blastodermic vesicle of the Marsupialia. A 

 knowledge of the embryonic layers which enter into the formation of 

 the yelk-bag of Anableps would also be a desideratum. 



The extension downwards of the intestine of the embryo oi Anableps 

 into the empty yelk-bag is also interesting and reminds one somewhat 

 of the peculiar i)rotrusion of the hind-gut of Embiotocoid embryos into 

 an inferior saccular diverticulum of the back part of the abdomen, 

 which is obviously not homologous, however, with the globular, bag- 

 like structure seen in the former. 



Wyman does not state whether he examined the surfaces of the ova- 

 rian membranes In the earliest stages of development of the papulifer- 

 ous sac to see if they did not present pits or crypts into which the 

 papilliie may have fitted. These papilla) are obviously in some way con- 

 nected either with the respiration of the foetal Anableps or with its nu- 

 trition in the same way as are the marginal lobes of the fins of the foetal 

 Embiotocoids. 



II. — The development of the Vivipahous Surf-perches or Em- 



BIOTOCID^ OF THE PACIFIC COAST. 



Dr. Girard* states that the discovery that these fishes were vivipa- 

 rous was made in May, 1853, in San Diego Bay, California, by Dr. 

 Thomas IT. Webb, whose manuscript journal is quoted by Girard. 



'Explorations and Surveys for a Railroad from the Mississippi River to the Pacific 

 Ocean. IV. Fishes. 4to. Washington, IS'jB. 



