620 HISTOllICAL GEOLOGY. 



like arrangement, but less perfectly, for the lower part of the caudal tin. 

 They gave the posterior part of the body great strength for sculling. It is 

 further to be observed that the open space along the c 'utir of the vertebral 

 column indicates a persistent notochord (cartilaginous), tlie spinous processes 

 being the only calcareous portions of the column. Fig. 974 represents a 

 Canada species of Chirolepis, a genus of the family Palaeoniscidae. Palceo- 

 niscus Devonicus of Clarke is another Devonian Ganoid, from the Portage of 

 New York. The species. Figs. 970, 971, 974, are from Scaumenac Bay. 



Selachians, or Sharks, were represented not only by fin-spines and teeth, 

 but also, in the Cleveland shale of Ohio, by impressions or remains of the 



nearly entire body. Two s[-eci- 

 978. mens of the latter are shown, 



much reduced, in Figs. 975, 977. 

 The largest yet found, Cladodus 

 Kepleri, had a length of six feet. 

 Newberry's figure of C. Fyleri, in 

 his Paleozoic Fishes of North 



Selachian.- Fig. 9TS,Acanthodesaffini3; o, scales, America, giveS it a length of 



natural size, whiteaves. 22 inches. It is referred to a 



new genus, Cladoselacha, by B. 

 Dean. The tooth, Fig. 976, is of the species Cladodus ClarJci of Claypole. 



Remains of a species of another genus, Acanthodes, related to the Sharks, 

 but having minute square or rhombic scales, has been found at Scaumenac 

 Bay. A small specimen is represented in Fig. 978. Other species of the 

 genus have been reported from New York and Pennsylvania. 



Characteristic Species. 



Genesee shales, — Orbicidoidea Lodensis, Discina truncata, Lingula spatulata (also 

 Portage), Chonetes lepidus (also Hamilton), Amboccelia umbonata (also Ham. & Mar.), 

 Leiorliynchus quadricostatum, Stroplialosia truncata (also Marcellus), Lunulicardium 

 fragile (Marcellus to Portage), Cardiola (Glyptocardia) speciosa (Ham. to Chemung), 

 Styliolina fissurella, Tentaculites gracilistriatus (also in the Marcellus), Orthoceras subu- 

 latum (also Marcellus), Goniatites complanatus (also Upper Ham. and Portage), G. dis- 

 coideus (Marc, Ham. also), G. intumescens { = G. Patersoni) (also Portage and Chemung) . 



Portage group. — Amboccelia umbonata, Grammysia subarcuata, Lunulicardium 

 fragile, L. acutirostrum, L. ornatum, Cardiola speciosa, St'jliolina fissurella, Bellerophon 

 natator, Coleolus acicida, Tentacidites gracilistriatus, Orthoceras pacator, Goni<itites 

 complanatus, G. intumescens, G. bicostatus, G. sinuosus. 



Ithaca beds (noted for the number of Brachiopods). — Lingula spatulata, Atrypa 

 reticularis, Spirifer mesacostalis and 5. mesastrialis, Cryptonella eudora, Stropheodonta 

 mucronata, Ehyyichonella pngnus, R. eximia, Productella speciosa, Leiorhynchus mesa- 

 costale, Orthis iynjyressa, Chonetes setiger us, C. scitulus. Crania; Lunulicardium fragile, 

 Schizodus quadrangidaris, Palceoneilo Jilosa, species of Leptodesma and Avicidopecten, 

 Grammysia subarcuata, Tentaculites spiculus, Orthoceras bebryx, 0. fulgidum. Sjmthio- 

 caris Emersoni Clarke, of the Portage, is described and figured in Am. Jour. Sc, xxiii., 

 1882. The Palceopalcemon was first described by Whitfield, in Am. Jorir. Sc, xix., 1880. 



The Naples beds, in the Portage, containing the Clymenia (Fig. 949), have afforded 

 also, according to J. M. Clarke (1891, '92), Palceoniscus Dpvonicus Clarke, Acanthodes 



)ia 



