Labyrinthici and Holconoti 377 



preaching about the back and on the -fins a black color, and a 

 remarkably vigorous fish. The young which I took from her 

 were in shape, save as to rotundity, perfect miniatures of the 

 mother, formed like her, and of the same general proportions, 

 except that the old one was (probably owing to her pregnancy) 

 much broader and wider between the top of the dorsal and the 

 ventral fins in proportion to her length than the young were. 

 As to color, they were in all respects like the mother, though the 

 shades were many degrees lighter. Indeed, they were in all 

 respects like their mother and like each other, the same pecu- 

 liar mouth, the same position and shape of the fins, and the 

 same eyes and gills, and there cannot remain in the mind of 

 any one who sees the fish in the same state that I did a single 

 doubt that these young were the offspring of the fish from whose 

 body I took them, and that this species of fish gives birth to her 

 young alive and perfectly formed, and adapted to seeking its own 

 livelihood in the water. The number of young in the bag was 

 nineteen (I fear I misstated the number in my former letter), 

 and every one as brisk and lively and as much at home in a bucket 

 of salt water as if they had been for months accustomed to the 

 water. The male fish that was caught was not quite as large 

 as the female, either in length or circumference, and altogether 

 a more slim fish. I think we. may reasonably expect to receive 

 the specimens by the first of December. But I can hardly 

 hope to get satisfactory specimens of the fish as I found it, with 

 young well grown, before the return of the same season, viz., 

 June. By that time I trust the facts will be fully decided, 

 and the results, as important as they may be, fully appreciated." 



Dr. Jackson's specimens came from Sausalito Bay, near 

 San Francisco. Soon after the publication of this letter a 

 similar discovery was made independently by Dr. William P. 

 Gibbons, of Alameda. Still other specimens were made known 

 in 1854 by Dr. Charles Girard, these having been collected in 

 connection with the United States Pacific Railroad Surveys. 

 The species first examined by Dr. Jackson was named by Agassiz 

 Embiotoca jacksoni. 



In. Professor Agassiz's comments on Dr. Jackson's discovery 

 he makes the following observations (Amer. Jour. Science and 

 Arts, 1854): 



