124 Eevieics — A. S. WoodicarcV s Catalogue of Fossil Fishes. 



As regards the first four subclasses wliicli possess a demonstrable 

 endoskeleton in the paired limbs, Mr, Woodward has constructed an 

 interesting table to express his view that in the evolution of their 

 members these groups form parallel series. For, as has been pretty- 

 well known to paleeichthyologists for some time back, the views of 

 Balfour and Mivart that the ordinary Shark-limb is a more archaic 

 and less specialized form than that of Ceratodus (archipterygium of 

 Gegenbaur) is directly contradicted by palaeontology. As Mr. 

 Woodward well puts it, " If in accordance with the present teaching 

 of embryological research, the paired limbs have been derived from 

 lateral folds, the primitive condition of these appendages still remains 

 undiscovered, and their evolution can only be traced from a com- 

 paratively advanced stage. All the most generalized early Paleozoic 

 fishes hitherto met with exhibit two pairs of limbs of the paddle-like 

 form termed archipterygium by Gegenbaur, and subsequent 

 specialization has resulted in the gradual atrophy of these limbs 

 usually with a concomitant development of the fringing dermal rays 

 (actinotrichia)." Eecentl}'^ an interesting attempt has been made by- 

 Prof Anton Fritsch to show that though Gegenbaur is undoubtedly- 

 right in holding the modern Shark-limb to be specialized from the 

 archipterygium, yet the archipterygium itself may have been originally- 

 developed from a series of parallel rays.^ And, as observed by Cope, 

 some remains of this ancient fin-fold may possibly be indicated by 

 the two ventral rows of spines in some Devonian Acanthodei. 



The present part contains the remainder of the ElasmohrancMi, 

 the JSolocepliali, the isolated Ichthyodorulites, the Ostracodermi, the 

 Dipnoi, and a part of the Tele-oatomi, including the Crossopterygii 

 and the Acipenseroid families Palseoniscidae and Platysomidse. 



Elasjviobranchii. 

 Here Mr. Woodward follows Liitken and Fritsch in including the 

 Acanthodei in this subclass, and as the want of evidence of any 

 opercular apparatus renders it probable that the branchial clefts 

 opened separately on the exterior, this may indeed be the best place 

 to put them in the meanwhile. The remarkable deviation from the 

 ordinary Elasmobranch type, exhibited by their paired fins, the 

 author explains as due to extreme specialization (abbreviation) and 

 his idea is that the Acanthodians " occupy the same position in the 

 Elasmobranch phylum that is held at the present day by the 

 Actinopterygians in that of Teleostomi." The account given of this 

 group is one of the most interesting sections of the book, and he gives 

 an original restoration of AcantJiodes Wardi, Eg., which is a con- 

 siderable improvement on the old and well-known figures of Koemer 

 and Liitken [A. Bronni), though the orbit is too small, the peculiar 

 fringe-like contour of the ventral fin is not given, and I am also 

 inclined to hold that in representing the fish with prominent branchial 

 " frills " after the manner of the recent CMamydoselache the author 

 is going beyond the legitimate limits of "restoration." The limita- 

 tion of the family term Acanthodidce to those genera with one dorsal 



1 " Fauna der Gaskohle," vol. iii. pt. i. pp. 44. 



