DEVELOPMENT OF SOME SILURIAN BRACHIOPODA 315 



Lingula gibbosa Hall No young shells obtained. 



Pholidops ovalis Hall " " " 



RUpidomella hybrida Sowerby . . Numerous inchoate specimens. 



Dalmanella elegantula Dalman . . " " " 



Orthis subnodosa Hall No young shells obtained. 



Bilobites bilobus Linnaeus .... " " 



Orthothetes tennis Hall " " " 



Orthothetes subplanus Conrad . . Full series showing development. 



Leptcena rhomboidalis Wilckens . . " " " 



Stropheodonta profunda Hall ... No young shells obtained. 



StrophonelLa striata Hall .... Full series, showing development. 



Strophonella semifasciata Hall . . . No young shells obtained. 



Plectambonites transversalis Dalman . " " 



Mimulus waldronensis Miller and Dyer One embryo. 



Chonetes nova-scoticus Hall .... No young shells obtained. 



Chonetes undulatus Hall .... " " " 



Dictyonella reticulata Hall .... Young shells not rare. 



Clorinda fornicata, var., Hall . . . No young shells obtained. 



Anastrophia internascens Hall . . . Young shells not rare. 



Camarotcechia neglecta Hall . . . Young shells very abundant. 



Camarotcechia acinus Hall .... 



Camarotcechia indianensis Hall . . 



Camarotcechia Whitii Hall . . . / 



Uncinulus Stricklandi Sowerby . . Mature form abundant ; no young 



shells obtained. 



RJiynchotreta cuneata Dalman . . . Young shells common. 



Atrypa reticularis Linnaeus . . . Young shells abundant. 



Zygospira minima Hall No young shells obtained. 



Atrypina disparilis Hall .... Young shells common. 



Homceospira evax Hall Young shells very abundant. 



Homceospira sobrina sp. n Young shells not rare. 



Nucleospira pisiformis Hall * ... 



Meristina rectirostris Hall .... Full series, showing development. 



Whitfieldella nitida Hall .... Numerous inchoate specimens. 



Meristina Maria Hall Incomplete series showing devel- 

 opment. 



Spirifer eudora Hall No young shells obtained. 



Spirifer crispus Hisinger .... Full series, showing development. 



Spirifer crispus, var. simplex, Hall . " " ** 



Spirifer radiatus Sowerby .... " " 



Reticularia bicostata, var. petila, Hall. *' " " 



* The mature characters of this species are assumed so early that the 

 youngest forms observed show no important differences from the adult. On 

 this account no discussion of its characters is given in the ensuing pages. 



