4 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



In two articles on Dinichthyid remains, published in 1905, Mr. L. 

 Hussakof -^ refers to them as " Placoderms," evidently using the term 

 in its familiar acceptation. Their position is also left undetermined by 

 Prof. E. Ray Lankester, in his interesting lectures on Extinct animals, 

 recently published.^ Dr. F. A. Lucas's popular treatise on Animals 

 before man in North America places them in association with lung- 

 fishes, in accordance with Smith Woodward's ideas. One other popular 

 handbook claims attention, not only because it is an extremely useful 

 work covering the whole subject of fishes, but also because of the 

 author's acquaintance with fossil as well as recent forms. We refer to 

 President D. S. Jordan's Guide to the study of fishes (New York, 

 1905), in the first volume of which (page 582) the relations of Ar- 

 throdires are discussed as follows : — 



" These monstrous creatures have been considered by Woodward and others as 

 mailed Dipnoans, but their singular jaws are quite unlike tliose of the Dipneusti, 

 and very remote from any structures in the ordinary fish. The turtle-like mandi- 

 bles seem to be formed of dermal elements, in which there lies little homology to 

 the jaws of a fish and not much more with the jaws of Dipnoan or shark. 



The relations with the Ostracophores are certainly remote, though nothing else 

 seems to be any nearer. They have no aflBnity with the true Ganoids, to which 

 vaguely limited group many writers have attached them. Nor is there any sure 

 foundation to the view adopted by Woodward, that they are to be considered as 

 armored offslioots of the Dipnoans." 



Again, at page 445 of the same volume, occurs this passage : — 



" These creatures have been often called ganoids, but with the true ganoids like 

 the garpike tliey have seemingly nothing in common. They are also different 

 from the Ostracophores. To regard them with Woodward as derived from ances- 

 tral Dipnoans is to give a possible guess as to their origin, and a very unsatis- 

 factory guess at that." 



Finally, reference may be made to a paper published early in the 

 present year, in which the writer^ endeavored to show that the denti- 

 tion of Arthrodires belongs distinctly to the Dipnoan type, and that 

 real homologies exist between their cranial roof-plates and those of 

 the living Neoceratodus. Indeed, the modern form was held to bear 

 as intimate structural resemblance to Coccosteans on the one hand, as 



1 Hussakof, L. Notes on the Devonian " Placoderm," Dinichthys intermedius 

 Newb. Bull. Amer. INIus. Nat. Hist., 1905, 21, p. 27-36. On the structure of two 

 imperfectly known Dinichthyids. Ibid., p. 409-414. 



2 Lankester, E. R. Extinct animals. New York, 1905, p. 256. 



8 Eastman, C R. Dipnoan affinities of Arthrodires. Amer. Journ. Sci., 1906, 

 ser. 4, 21, p. 77-89. 



