Biographical Sketch 11 



HIS TEXT BOOK "FISHES, LIVING AND FOSSIL" 



1895 



By 1895, at the age of 28 and after scarcely more than five years of active work in 

 ichthyology, he had already accumulated enough illustrative material along all the lines 

 previously mentioned to publish his notable text-book, "Fishes Living and Fossil : An 

 Outline of their Forms and Probable Relationships" in the Columbia University Biological 

 Series. This text-book, like everything else Dean wrote, was marked by its extreme com- 

 pactness and clarity; but it has also been especially prized for the large number of care- 

 fully drawn comparative figures and highly useful tables. On the other hand, the book 

 was very sketchy in its treatment of the teleosts, containing ideas as to the relationships 

 of the catfishes and other teleosts which have not been supported by later investigations. 

 The fact is that Dean was interested primarily in the archaic fishes of all groups and that, 

 this being a field wide enough even for his amazing activities, he refrained from wandering 

 far among the swarming tribes of the modernized teleosts. Somewhat later he delegated 

 the preparation of a general review of the phylogeny and classification of the teleosts to 

 one of his students, the present writer. 



PALAEOSPOKDTWS AND THE DEVELOPMENT OF THE CYCLOSTOMES 



1896-1904 



The year 1896 brought his first paper on Palaeospondylus, which was a puzzling little 

 Devonian chordate supposed by Traquair to be related to the cyclostomes. "Is Palaeo- 

 spondylus a Cyclostome?" he queried, and in several papers, culminating in his memoir 

 on the subject in 1900, he stoutly supported the opinion that it was not. This last paper 

 contains some of his most beautifully executed lithographic plates, showing the finer 

 details of this enigmatical fossil. However, according to Stensio's recent researches and 

 in the light of much fuller knowledge of the Ostracoderms, Palaeospondylus may after 

 all be more nearly related to the cyclostomes than Dean was willing to admit. 



Meanwhile the subjects previously noted kept crowding each other in his bibliog- 

 raphy of subsequent years. However, it should be noted that both because Dean spent 

 considerable part of his time in the field as well as because he was extremely concise and 

 pithy in his writings, his bibliography rarely runs to more than ten short papers in a year. 

 Perhaps Dean's interest in the fossil Palaeospondylus roused him to special exertions to 

 secure the embryology of certain of the existing cyclostomes. At any rate during the 

 next few years (1895 to 1899) he combed the waters of Alaska, California, and Japan for 

 eggs of the hagfishes which sometimes came up on the fisherman's lines, entangled in the 

 slime exuded from the hagfishes themselves. As these priceless relics were worked over. 

 Dean issued a series of papers on the development of Bdellostoma and related forms begin- 

 ning in 1897 and running at intervals till 1904. His most important contribution in this 

 field was his memoir on the embryology of Bdellostoma stouti (1899) in which he was able 

 to muster an imposing and closely knit developmental series of this most rare and significant 

 material. He was able to show, among other things, that the hagfish development stood 



