236 



PALAEOZOIC TIME UPPER SILURIAN. 



trail of a sea-worm, or Annelid, reduced one-half. There were also 

 Orthocerata and Trilobites. 



Characteristic Species. 

 1. Radiates. — (o.) Polyps.— Figs. 365, 366, Zaphrentis (Caninia) UlateraUs ; 

 367, Palseocyclus rotuloicles, different views, from New York; 368, a branching 

 Figs. 365-369. 



Radiates. 



Chsetetes. 

 Crinoids. 



found in 



—Figs. 365, 366, Zaphrentis bilateralis; 367, Palseocyclus rotuloides; 368, a, Chfe- 

 tetes ; 369, a, Graptolithus Clintoneusis. . 



(6.) Acalepks. — 369, a, Graptolithus Clintonensis. (c.) Echinoderms : 

 —A few species are known : fragments are common, and they are often 

 the iron-ore as well as in the limestones. 



Fiss. 370-382. 



Mollttsks.— Figs. 370, a, Fenestella ? prisca; 371, Pentamerus oblongus; 372, 373, part of 

 casts of the interior ; 374, 375, Atrypa reticularis ; 376, 377, Athyris (formerly Atrypa) 

 cpngesta; 378, Chonetes cornuta; 379, Avicula rhomboidea ; 380, Cyclonema cancellata; 

 381. track of a Bivalve (X^); 382, track of an Annelid ? ( X % )■ 



2. Mollusks. — (a.) Bryozoans — Fig. 370, Fenestella? prisca. 



