CONTENTS xiii 



Page 

 3. Revision of the Families of Loop-bearing Brachi- 

 OPODA — Continued 



Morphogeny from Gwynia to Dallina 303 



Morphogeny from Gwynia to Mayellania 303 



Conclusions 304 



Classification 305 



Family Terebratulidse Gray 306 



Centronellinse Waagen 306 



StringocephalinfB Dall 307 



Terebratulinie Dall 307 



Dyscoliinse (^Dyscoliidae Fischer and (Ehlert 



emend.) 307 



Family Terebratellidae King emend 307 



Dallininae n. sub.-fam 307 



JMagellaniinge n. sub.-fam 308 



Megathyrin« Dall 308 



References 308 



4. Development of some Silurian Brachiopoda . . 310 



Introduction 310 



List of the Brachiopoda occurring in the Niagara 



Shales at Waldron, Indiana 314 



Discussions of the Species 317 



Crania siluriana Hall, 1863 317 



Dalmanella elegantula Dalman, 1827 317 



Specific Characters 318 



Mature Form 318 



Incipient Form 319 



Developmental Changes 320 



General Form and Outline 320 



Beaks 320 



Foramen 320 



Plications 321 



Rhipidomella hybrida Sowerhy, 1839 321 



Leptcena rhomboidalis Wilckens, 1769 322 



Specific Characters 323 



Mature Form 323 



Incipient Form 323 



Developmental Changes 324 



Development of Leptcena rhomboidalis . . . 325 



Orthothetes xubplavus Conrad, 1842 ...... 327 



Specific Characters 328 



Mature Form 328 



Incipient Form . , 328 



Developmental Variations 329 



Strophonella xtriata Hall, 1843 330 



Specific Characters 331 



