638 



INDEX 



Zygospira, 231, 246, 256, 270, 413, 415, 

 416. 



brachial supports in, 415. 

 brachidium in, 284. 



Schuchert, 282. 

 development in, 411. 



of brachial supports in, 410. 

 minima, 315. 



modesta, variation in brachial sup- 

 ports of, 416. 



whorls in spirals of, 415. 

 Nicoletti, loop in, 413, 416. 



rudimentary spirals in, 415. 

 ontogeny and phylogeny of, 417. 

 pedicle-opening in, 242. 



posterior transverse band in, 416. 

 primitive arm support in, 411. 

 recurvirostris, 416. 



brachidium of, 284. 



development of brachial sup- 

 ports in, 413, 



lamellae in spirals of, 415. 



loop in, 413, 416. 



transverse band in, 413. 

 resorption of loop in, 283. 

 Sqffbrdi, loop in, 413, 416. 



rudimentary spirals in, 415. 

 to Atrypa, evolution from, 417. 

 trocholophus stage in, 283. 

 whorls to a cone of, 415. 



