ORISKANY FAUNA OF BECRAFT MOUNTAIN 17 



frontal margin of the cephalon is possessed in less degree and different 

 cpiality by several antecedent species. Thus as far back as the Dal. 

 viffilans Hall, and Dal. verrucosus Hall of the later Niagara 

 (Waldron) fauna there is a pronounced development of a short and simple 

 spatulate process at the anterior extremity. In the Dal. pleuroptyx 

 Conrad, of the Helderbergian, this process becomes broadened and divided, 

 the divisions taking on the character of those in Dal. stemmatns, 

 though being less numerous and of less extent along the border. In 

 Dal. anchiops Green, of the Schoharie grit, a similar character is 

 manifested, 1 extending for a short distance on either side of the extremity. 

 Dalmanites (Odontocephalus) selenurus Eaton, of the 

 Onondaga limestone, has the frontal margin developed by perforation into 

 incisor-like processes, which again extend but a short distance from the 

 extremity, while in Dal (Corycephalus) regalis Hall, of the 

 Schoharie grit, the processes are blunt, distant and extend to the ends 

 of the cheek spines. In the limestone beds at Port Jervis, the " trilo- 

 bite beds " of Barrett, are the species Dal. dentatus Barrett and 

 Dal. dolphi Clarke, the former with a row of pointed triangular pro- 

 cesses extending nearly to the extremities of the cheek spines, the latter 

 with a stronger compound anterior process and two or three sharp lateral 

 processes on each side. Thus the marginal ornamentation of the head 

 is seen to be subject to much variation, and from the simple anterior 

 extension of the frontal border manifested in some of the late Siluric 

 species, through the Dal. pleuroptyx of the early Devonic into 

 Dal. stemmatus of the Oriskany, there has been a simple intensi- 

 fication and extension of the type of crenulate ornament. Here, however, 

 the line ends, to be replaced and followed by the various phases above 

 mentioned. 



As to the employment of the term S y n p h o r i a , which is used 

 in the title of this species, a few remarks may be made. To some of 

 the ornamental expressions of Dalmanites referred to, generic or 

 subgeneric terms have been applied, e. g., Odontocephalus for 

 Dal. selenurus, Corycephalus for Dal. regalis, etc. It 



l See Paleontology of New York. v. 7, pi. 10, fig. 11. 



