CONTENTS. 7 



Zoological discussion — Continued. 



The brachiopod shell — Continued. Page. 



Vascular markings 311 



Atremata 311 



Neotremata 311 



Protremata 311 



Muscle scars 312 



Atremata 312 



Neotremata 312 



Protremata- 313 



Pedicle tube and aperture 314 



Atremata 314 



Neotremata 314 



Protremata 315 



Old-age characters 315 



Distribution in Cambrian strata 315 



Evolution of the Cambrian Brachiopoda 316 



Schematic diagram 316 



Atremata 318 



Neotremata 319 



Protremata 319 



Classification 321 



Order Atremata 322 



Superfamily Rustellacea 322 



Family Rustellidee 322 



Family Paterinidse 322 



Superfamily Obolacea 322 



Family Curticiidse 322 



Family Obolidse 322 



Subfamily Obolinae 322 



Subfamily Elkaniinse 323 



Subfamily Neobolinse 323 



Subfamily Biciinae 323 



Superfamily Kutorginacea 323 



Family Kutorginidse 323 



Family Schuchertinidse 323 



Order Neotremata 323 



Superfamily Siphonotretacea 324 



Family ObolelHdse 324 



Family Siphonotretidse 324 



Superfamily Acrotretacea 324 



Family Acrotretidse 324 



Subfamily Acrothelinie 324 



Subfamily Acrotretina; 324 



Superfamily Discinacea 325 



Family Discinidpe 325 



Superfamily Craniacea 325 



Family Craniidse 325 



Order Protremata 325 



Superfamily Orthacea 325 



Family Billingsellidfe 325 



Subfamily Nisusiinse 325 



Subfamily Billingsellinse 325 



Subfamily Eoorthinse 326 



Superfamily Strophomenacea 326 



Family Strophomenid^ 326 



Subfamily Rafinesquinse 326 



Superfamily Pentameracea 326 



Family Sjmtrophiidse .' 326 



Description of genera and species "■ 327 



Rustella Walcott 327 



Mickwitzia Schmidt 329 



a The list of species on pp. 98-109 gives the names of all the species in the order in which they appear in the monograph and also not only the 

 page but the illustration reference and other information. It should therefore be of more value to the student than a merelist of speciesin these 

 contents, and such a list has accordingly been omitted. The pages upon which the genera and subgenera are described are not shown in the list on 

 pp. 9S-109; therefore these are shown here. 



