550 HISTORICAL GEOLOGY. 



Animals. 1. Hydrozoans. — Fig. 750, Graptolithus Clintonensis H. 



2. Actinozoans. — Figs. 746, 747, Zaphrentis bilateraUs H. ; Favosites favosiis, Favi- 

 stella favosidea H., Palceocydus rotuloides H., Cannapora j^mciformis H., Halysites 

 escharoides Lamk. , H. catenulatus, species of Cyathophyllum, Streptelasma, Aulopora, 

 Diphyphyllum. 



3. Echinoderms. — Caryocrinus, but rare. 



4. Molluscoids. — (a) Bryozoans. — Fig. 751, Fenestella prisca Lonsdale ; Ptilodictya, 

 Stictopora, many species. 



(6) Brachiopods. — Species of Lingula, Orthis, Plectambonites, Bhynchonella, Spiri- 

 fer, Chonetes, and Pentamerus ; Fig. 752, Pentamerus oblongus Sow. ; some specimens 

 are twice the size of the figure ; the interior of the shell is shown in Figs. 753, 753 a ; 

 Figs. 754, a, Atrypa reticularis Linn. ; Figs. 755, a, Hyattella congesta Con. ( = Cama- 

 rella congesta); Fig. 756, Chonetes curnutus. 



5. Mollusks. — (a) Lamellibranchs. — Fig. 757, Avicula rhomboidea H. ; A. emacerata 

 Con., Tellinomya machmriformis H., abundant. 



(6) Gastropods. — Fig. 758, Cyclonema cancellatuni H. ; Bucania trilobata of the 

 Medina also occurs here, besides other Gastropods. 



6. Crustaceans. — Homalonotus delphinocephalus, Calymene Clintoni Van. , C. Niaga- 

 rensis, Cerauriis Niagarensis H., Phacops trisulcata H. 



(a) Ostracoids, or Bivalve Crustaceans. — Fig. 789, Beyrichia symmetrica H., showing 

 one of the valves; 789 a, same, natural size; B. spinosa H., Lockport. (6) Ceratio- 

 carids. — Ceratiocaris Deioeyi H., specimens of the caudal spine, formerly supposed to 

 belong to a Fish, and named Onchus Deioeyi. OncJms Clintoni of Claypole is from the 

 Iron Sandstone stratum of Perry County, Pa. (1884, 1885) ; that it belonged to a Fish is 

 not certain. 



7. Eurypterids (Limuloids). — Eurypterus prominens 'R. 



Among the Clinton species are the following from the Lower Silurian : Orthis {Platy- 

 strophia) biforata, Leptcena (Plectambonites) sericea., Bellerophon bilobatiis, Calymene 

 callicephala. The following are known in Europe : Orthis biforata, Atrypa reticularis, 

 Codospira {Atrypa) hemisphoerica Murch., Spirifer radiatus Sow., Pentamerus oblongus. 



3. Niagara Epoch. 



1. Spongiozoans. — Astrceospongia, Astylospongia, Palceomanon of Roemer in Tennes- 

 see, in the upper part of the Niagara (or Meniscus) limestone ; Astrceospongia meniscus is 

 the most abundant. {Sil. Faun. W. Tenn., 1870.) 



2. Hydrozoans. — Dictyonema, Gomvuon ; Fig. 766, Stromatopora concentrica Gol^. 



3. Actinozoans. — Fig. 761, Chonophyllum Niagarense H. ; Streptelasma calyculus H., 

 Astrocerium venustum H., masses often 2 or 3 feet in diameter ; Strombodes gracilis Bill. ; 

 762, Favosites Niagarensis H. ; F. Gothlandicus Lamk., F. vemistus H. ; 763, Halysites 

 catenulatus Linn., H. escharoides Lamk., H. agglomeratus H. ; 764, Heliolites spiniporus 

 H. ; 765, an enlarged view, showing the 12-rayed cells, and the interval of a cellular char- 

 acter separating them, both of which are distinguishing characteristics of the genus Helio- 

 lites ; H. interstinctus Linn., H. pyriformis Guettard, Syringopora retiformis Bill., 

 8. multicaulis H., Aulopora precia H., A. repens. 



4. Echinoderms. — Fig. 767, Ichthyocrinus Icevis Con., Lockport, sometimes twice as 

 large as the figure ; 768, Caryocrinus ornatus Say, New York, Wisconsin, and Tennessee, 

 named from Carya, the hickory-nut ; 769, Stephanocrinus angulatus Con., Lockport ; a, 

 part of the stem, enlarged ; b, joint ; c, base of the body, showing the 3 pieces of which it 

 consists ; species of Melocrinus, Eucalyptocrinus decorus Phillips, New York, Kentucky, 

 Tennessee; Camarocrimis Saffordi H., Tennessee; Lecanocrinus, etc. Also Fig. 444 

 (page 429), the Cystoid, Callocystites Jewetti H. ; Apiocystites elegans H., A. Canadensis, 

 and A. Huronensis of Billings, from Anticosti. Troostocrinus subcylindricus H. and 



