ILLUSTRATIONS 



Page. 



Plate I. Diagram illustratiDg geologic diatributiou of families 134 



Fig. 1. Diagram giving the geologic distribution of the brachiopod orders ... 96 



2. Stages of growth of the lophophore iu Thecidea, Cistella, and Mega- 



thyris 108 



3. Stages of growth of the lophophore iu the Terebratellidne and Tere- 



bratulidte 109 



4. Metamorjihoses of the brachidium in Dielasma tiirgida 110 



5. Early stages of the lophophore of Glottidia and adult brachia in 



Liugula and Hemithyris 110 



6. Metamorphoses of the brachidium of Zygospira and the brachidium 



of Rhyuchospira 111 



7 



