1896.] NATURAL SCIENCES OF PHILADELPHIA. 227 



In 1880, the National Government was desirous of having investi- 

 gations prosecuted in behalf of the United States Fish Commission on 

 the life-history of the American food-fishes and other aquatic animals, 

 especially their embryology and growth, the character of their food 

 in the early as well as the later stages of life. In the judgment of 

 Prof. Baird, who was at that time Commissioner, no one in the 

 country possessed the qualifications to meet the provisions of such 

 investigations in so high a degree as Dr. Ryder. 



He was at once invited to undertake the work, which not only 

 gave him an opportunity of systematizing his studies (these were 

 already embracing the higher problems in biology), but had the 

 advantage of placing him in a better paid position. 



It is true that up to this date Ryder had given no special atten- 

 tion to fishes, but he had obtained a general knowledge of the sub- 

 ject at the Academy, his inherited talent for invention lent itself 

 readily to the details of field-work, while his acquaintance with 

 the lower forms of aquatic life fitted him for the study of the food 

 of fishes, the study of their young stages, their parasites, etc' 



Dr. Ryder always referred to this period with interest. His first 

 detail was to the field, but in 1882, Prof. Baird transferred him to 

 the National Museum, occasionally only, assigning him to field- 

 work. He was extraordinarily active during the six years he re- 

 mained on the Commission. He contributed twenty-nine papers on 

 the oyster and oyster-culture, and fifty papers on the development 

 of fishes, their food material and methods of development. All his 

 contributions were carefully prepared and showed extensive knowl- 

 edge of the subjects treated. He discovered, in 1888, a byssus in 

 a young stage of the long clam Mya arenaria. Prof. Baird, in 

 commenting on this discovery in his report for that year, believed " it 

 to be of economic importance since the young individuals now can 

 be freely handled and transported." jNIr. Bashford Dean remarks : 

 " I have heard it said that Dr. Ryder had, in his scientific work, 

 grown up with the Commission ; it might, I think, be said even as 

 justly that the Commission had, in a measure, grown up with him."* 

 His personality and methods had stamped themselves upon every 



'(1) The following papers, prior to 1880, related to Dr. Ryder's contribu- 

 tion to ichthyology : "On the Origin of Bilateral Symmetry and the Numer- 

 ous Segments of the Soft Rays of Fishes ; " " Phosphorescence of very Young 

 Fishes ; " " The Psorosperms found in Aphredodirus sayanus." 



* Memorial Pamphlet. 



