460 CHAIJACTERS OF PALEOZOIC FISHES COPE, 



RHIPIDOPTERYGTA. 



The order;', of Kliipitloptorygia are the following. They all have 

 actiuotrichia in place of tin-rays: 



I. Paiiod fins with tbe basilars arranged on each side of the median axis, or arcliip- 

 terygial. 



Median fins with basilars Taxistia 



II. Paired fins with the basilars arranged fan-shaped at the end of the short axis. 



Median fins with basilars lihipidiaiia 



Median fins withont, caudal fin with, basilars Jetiiiistia 



The Taxistia inchules but one family, the Holoi)tychii(]a^, which is of 

 Devonic and Carbonic age. The Khipidistia includes the Tristichop- 

 teridiB from the Devonic and Carbonic ; the Osteolepida^, from the same, 

 and possibly the Ouychodontida^ which are Devonic. 



The Actinistia includes the single family of the Ccplacanthidai, which 

 api)ears in the Lower Carbonic and ranges to the Ui)per Cretacic in both 

 Europe and America. 



In all of the Khipidopterygia the tail is either lieterocercal or diphy- 

 cercal and the chordadorsalis persists. The scales have a layer of 

 ganoine, which extends also on the head. The latter has a well-defined 

 persistent transverse suture separating the parietal from the frontal 

 elements. 



The Grossopieriiijid includes two orders, as follows: 



Baseosts and axonosts well developed ; actinotrichia ; no fin rays ; pectorals nni- 



basal Jlaplixtia 



Baseosts rudiiiiental ; fin rays; pectorals tribaaal Cladistia 



Bnt one family is included in the Haplistia, the Tarasiida?, from the 

 Lower Carbonic of Scotland. The Cladistia are represented by a family 

 which is not known in the fossil state, the Polypterida^, of the rivers of 

 Africa. The vertebra' in this genus are ossified and biconcave. 



The Podopterygia has also two orders. They are thus defined : 



Branch iostogal rays present Lijsopleri 



No branchiostegal rays Choudroslei 



In these orders the notochord is ])ersistent, and there are either actino- 

 trichia or fin-rays which are more numerous than the baseosts. Tail 

 heterocercal or diphycercal. 



VH. — On new Species of Platysomidte. 



Platysomus palmaris sp. nov. 



This Species is represented by abont a hundred fragments of 

 bodies of various sizes, some of which include the scapular arch, but 

 none the fins. All tlie fragments are covered with scales, and in a 

 number of tliem the median line of the belly is ])reserved. In the scap- 

 ular ar{;h the character of the allied forms is observed in the i)resence 



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