844 DR RAMSAY H. TRAQUAIR ON FOSSIL FISHES COLLECTED BY THE 



Lappet-like appearance of the flaps, which I have interpreted as pectoral fins, would give 

 a new and important corroboration to the lateral fold theory of the paired limbs, and 

 would present us with a " ptj^chopterygium " still more archseic than the pectorals of 

 Cladoselache, as described and interpreted by Bashford Dean and others. 



Whether the Ccelolepidge are admissible to a place among the Selachii or not, the 

 nature of their dermal hard parts points directly to an Elasmobranch affinity and Elasmo- 

 branch derivation. But their "primitive" nature now seems to me, on reconsideration 

 of the subject, extremely doubtful. In fact, the depressed configuration of the anterior 

 part of the fish, the absence of teeth, and of ventral, dorsal, and anal fins seem to me to 

 be rather marks of a very considerable specialisation than of archseic simplicity. In this 

 way the lappct-like fin-flap may well represent a degenerate form of pectoral fin instead 

 of an original ptychopterygeal form of that member. 



And as the Ccelolepida? seem also to be so inseparably linked to a series of organisms 

 whose typical representatives can hardly be looked upon as Selachii, hardly even as 

 Elasmobranchs, I prefer to consider them as having definitely split off from the last 

 named sub-class, from which they doubtless originally came. 



The Drepanaspid^e. 



We may now take up the consideration of the Drepanaspidae, a family the sole 

 representative of which is the singular genus Drepanaspis of Schliiter, from the Lower 

 Devonian slates of Gmiinden, in Western Germany. 



Drepanaspis Gmiindenensis has hitherto been scarcely known to science. It was 

 named, but very imperfectly described, also without figures, in 1887 by Prof. Sciiluter 

 of Bonn (xxx.), who seemed to consider it as allied to Ceplialaspis. In Mr Smith Wood- 

 ward's Catalogue, Part II. p. 311, it is only mentioned by name and placed along 

 with a number of other imperfectly known forms (Aspidichthys, Anomalichthys, &c), 

 which he considered as " perhaps for the most part " referable to the Coccosteida:. la 

 1896 I noticed the fish before this Society,* and expressed the opinion that its affinities 

 lay rather with the Pteraspidse, a view which I am now prepared to defend and con- 

 firm, as well as to point out that on the other hand Drepanaspis is likewise related to 

 the Ccelolepidae. 



I have now, by the help of Mr B. Sturtz of Bonn, got together, in the Edinburgh 

 Museum of Science and Art, an important series of specimens of Drepanaspis from 

 Gmiinden, and I have also to thank my friend, Prof. 0. Jaekel, for procuring for me some 

 beautiful casts of examples in the Natural History Museum at Berlin, and also in the 

 collection of the Geological Survey in that city. I hope presently to use this material 

 for a more exhaustive description of this remarkable form ; meanwhile I shall indicate 

 the principal points in its construction, as far as ascertainable, by the aid of the accom- 

 panying restored sketch of its dorsal aspect. 



* Nature, vol. liv., 1896, p. 263. 



