PALEOZOIC TIME — DEVONIAN. 



599 



phalus, Bellerophon (many species), MurcMsonia (but one), Loxonema (many), 

 with also the Devonian and Carboniferous genus Macroclieilus. Pteropods 

 were still represented by Tentaculites, Hyolithes, and Conularia, and also by 

 species of Styliolina (Fig. 916), Coleolus, etc. StylioUna is like Tentaculites, 

 but has a smooth shell. 



Under Cephalopods, the old genus, OrtJioceras, had 29 described species 

 in 1880 (to 30 in the Corniferous); with these were species of GomjJhoceras, 

 Cyrtoceras, and Gyroceras. The Nau- 

 tiloid, Nephriticeras maximum occurs 

 over a foot in diameter. The genus 

 Goniatites, first known from the Cor- 

 niferous group, has a number of spe- 

 cies ; G. Vamixemi (Fig. 917) is one 

 of the earliest, being from the Mar- 

 cellus shale; it has only one flexure 

 in the septa, as shown in Fig. 917 a, 

 a mark of its antiquity; and it has 

 been made, on this account, by Hyatt, 

 the type of the new genus Agonia- 

 tites. The largest specimens are a 

 foot or more in diameter. A straight 

 form of Goniatites, Bactrites davus 

 H., has been found in the New York 

 Marcellus shale. 



Cephalopod. - 



-Figs. 917, a, Goniatites Vanuxemi. 

 Meek. 



918-919. 



6. Crustaceans. — The most characteristic species of Trilobite, Phacops rana 

 of Green ( = P. bufo), is represented in Fig. 918; its maximum length is 

 eight inches. The genus Dalmanites, which had nearly 25 Corniferous 

 species, has five described from the Hamilton; the pygi- 

 dium of D. Bootlii Green is represented on page 587, 

 and that of the variety calliteles, in Fig. 919. Other genera 

 are Homalonotus (which has a species 15 inches long), 

 Proetus, and Acidaspis. Fig. 880 (page 587) is the pygi- 

 dium of A. Romingeri. There is also a species of the 

 European genus Bronteus,S. Tullius H., found in the Tully 

 limestone. Out of all the genera of Trilobites existing 

 during the Hamilton and earlier geological time, only 

 Phacops and Cyphaspis have species reported from the later 

 Devonian. Others no doubt existed ; but still the decline 

 of what was once the leading life of the seas is strongly 

 manifested. The dash for ornamentation in the early and 

 middle Devonian was a mark of luxuriant, rather than 

 natural progress, and the same appears in the size of many 

 of the species. 



Phyllopods, of the Ceratiocarid type, are of several kinds. Fig. 920 

 represents an Echinocaris, one specimen of which, figured by Hall, from 



Fig. 91S, Phacops ra- 

 na ; 919, pygidium 

 of Dalmanites cal- 

 liteles (x|). Meek. 



