INTRODUCTION 



The value to science of the Bashford Dean Memorial Volume will be apparent chiefly 

 to those who will build further upon it as a foundation; but it is also of historical interest 

 as a document both of science and of civili2ation as they were during the latter half of the 

 nineteenth century and during the first decade or two of the twentieth century. In that 

 period descriptive embryology held a high place in the interest of zoologists and though 

 many of its problems still call for more complete answers, it helped to lead the way for 

 studies on cell lineage and on the mechanism of cell division and eventually led to the 

 recognition of the significance of chromosomes. But Bashford Dean, following closely in 

 the footsteps of Balfour, Dohrn, and von Kupfer, collected and studied his fossil and 

 recent fishes and amassed his material illustrating the embryology of fishes, primarily 

 because he was interested in evolution in general and especially in the origin, rise and 

 branching of the major groups of fishes. And since the known species of fishes number far 

 too many thousands to be investigated by one man, he diligently sought out and concen- 

 trated his efforts on the oldest known fossil fishes and on the most archaic and primitive 

 fishes of the present day. These included the lampreys and hagfishes (cyclostomes), the 

 frilled shark, the cestraciont or heterodont sharks, the chimaeroids and the survivors of 

 the ancient lungfishes and ganoids, especially Acipenser, Polyodon, Polypterus, Lepidosteus, 

 and Amia. 



In search of material. Dean made voyages to various parts of the world but, as it was 

 manifestly impossible for him to collect continuously, he availed himself freely of the then 

 active international cooperation of Japanese, American, German, and English scientists in 

 the collection and exchange of material. He also assigned many special problems to his 

 students — N. R. Harrington, L. Hussakof, W. E. Kellicott, R. C. Osburn, C. R. Stockard, 

 W. K. Gregory and B. G. Smith. 



In the period between 1891 and 1912, Dean published his memoirs and papers on the 

 oldest fossil sharks, on the fin'fcld origin of the paired fins, on the embryology of the 

 hagfishes, on chimaeroid fishes and their development and on the embryology of the 

 Ganoids — Aci^e?iser, Amia and Lepidosteus. Meanwhile, as traced in Article I of this 

 volume, Dean's abiding interest in the collection and the history of arms and armor 

 culminated in his career as Curator of Arms and Armor in the Metropolitan Museum of 

 Art. These duties, together with his responsibility for bringing the Bibliography of 

 Fishes to publication, conspired to delay the completion of his later zoological projects. 

 After his retirement from the curatorship in the Metropolitan Museum in November, 

 1927, Dean planned to take up and finish his long'delayed work on certain archaic fishes 

 for which material had been collected in Japan years before. This plan was broken off 

 by his untimely death on December 6, 1928. 



After Dr. Dean's death, examination of his scientific relicta brought to light a large 

 amount of zoological materials, consisting of notes, photographs, drawings done in the best 

 Japanese technique (of which he himself was a master), and specimens of certain archaic 

 sharks and of their eggs and embryos. It was soon seen that these would be lost to science 



