j/O Sketch of the Progress of North American [October, 



phioxus lanceolatus, as observed by him in three adults taken at 

 Fort Wool in twelve to fifteen fathoms of water, and in twenty 

 young secured by surface dredging. The lancelet swims with a 

 graceful, undulating motion, and can disappear from sight be- 

 neath the sand almost instantaneously. It swims indifferently 

 upon back or belly, and when excited is able to dart about with 

 extreme rapidity. The writer believes the ova to issue from the 

 branchiopore, and states that it is questionable whether the ante- 

 rior pigment-spot of the spinal cord is of any more value than 

 any of the other pigment-spots of the nervous system. 



The question, " Do flying fish fly ?" is answered in the affirma- 

 tive by C. O. Whitman, who declares that during a voyage from 

 San Francisco to Yokohama, he several times distinctly saw the 

 individual flaps of the large pectorals, while the ventrals were 

 held in quiet expansion. The longest flight observed lasted forty 

 seconds, and was certainly over eight hundred feet. 



The principal, almost the only contributor to the embryologi- 

 cal knowledge of fishes, has been the indefatigable J. A. Ryder, 

 of the Fish Commission. In the course of his investigations during 

 the past year, he has elucidated many points in the developmental 

 history of the shad, cod, salmon, top-minnow, stickleback, sea- 

 horse, garfish and other fishes. The range of his observations 

 has, in fact, been sufficiently extensive to warrant him in arriving 

 at certain general conclusions, some of which contravene those of 

 previous observers. When it is remembered that the only mate- 

 rial at the command of most biologists who have worked upon 

 the eggs and embryos of fishes, has been preserved in spirits for 

 more .or less time, while Professor Ryder has all along been sup- 

 plied with fresh material in large quantity through the Fish Com- 

 mission, it will be evident that his conclusions are entitled to 

 great weight. He finds that in the Teleostean fishes and in stur- 

 geons, the segmentation-cavity is not obliterated, but gradually 

 thins out and grows around the yelk between the epiblast and 

 hypoblast, forming a paravitelline space which persists for at least 

 two weeks after the embryo leaves the c^. Around the edge of 

 the blastoderm a thickened rim or annulus is developed in both 

 the types above mentioned, and limits the paravitelline cavity. 

 The cleavage of the germ disk is regular, but the embryo agrees 

 with that of the Selachians in developing at the edge of the disk, 

 instead of in the center as is the case in birds and reptiles. A 



