DEVONIAN FISHES OF IOWA 227 



dorf, in Rhenish Prussia, and belongs to the Schulze collection 

 in the Museum of Comparative Zoology at Cambridge. 



Other fragmentary Dipterine remains are found in the same 

 locality, in particular those examples of calcified labial cartilage 

 which were recognized by Traquair as belonging to some un- 

 known genus allied to Dipterus, Ctenodus, etc., and upon the evi- 

 dence of which he framed the provisional genus Ganorhynchus. 

 It may be that several genera possessed labial cartilage of this 

 nature, although it does not occur in Dipterus proper, and has 

 not hitherto been observed in Scaumenacia. Certain it is, 

 however, that the arrangement of cranial roofing plates in the 

 Australian species described as Ganorhynchus suessmilchi* is 

 remarkably suggestive of Scaumenacia, so much so in fact that 

 one is obliged to assume that a form of lip cartilage not unlike 

 that of Ganorhynchus was actually present in the Canadian 

 genus, but has failed as yet of recognition. A single tooth of 

 Dipterus, doubtfully determined as D. valenciennesi, is recorded 

 by Jaekelf from the marine Middle Devonian of Rhineland, 

 and another, said to be distinct from any described species, is 

 reported by Fourmaier| from the Upper Devonian of Bilstein, 

 in Belgium. 



Formation and locality. Middle Devonian; Berndorf, Eifel 

 District. 



Genus CONCHODIS M'Coy. 

 (Syn. Cheirodus Pander non M'Coy) 



A genus known only by detached dental plates which exhibit 

 intermediate characters between Dipterus and Synthetodus. 

 The plates agree in general form with those of Dipterus, and 

 were apparently arranged in the mouth after the same fashion ; 

 but their functional surface is almost or quite smooth, and with 

 but few short and obsolescent radiating ridges at the outer 

 border. In some species the vestigial plicae are represented by 

 two or three short rows of coarse tubercles. Mandibular dental 



*R. Etheridge, Jr., Cranial buckler of a Dipnoan fish from the Devonian of 

 New South Wales. Records Australian Museum 1906, 6, pp. 129-132, pi. 28. 



t Jaekel, 0., Abstract in Zeitschr. deutsch. geol. Ges. 1899, 51, pp. 37, 38 Pro- 

 tokoll. 



JFourmaier. P., Decouverte de Dipterus a Bilstein. Ann. Soc. G6ol. Beige, etc. 

 1899, 26, p. cxiii. 



