DEVELOPMENT OF SOME SILURIAN BRACHIOPODA 315 



Lingula glhbosa Hall .... 

 Pholidops oralis Hall 

 Rhipidomella hybrida Sowerby 

 Dalmanella elegantula Dalman 

 Orthis subnodosa Hall . . . 

 Bilobites bilobus Linnaeus 

 Orthothetes tenuis Hall . 

 Orthothetes subplanus Conrad • 

 Leptcena rhornboidalis Wilckens 

 Stropheodonta profunda Hall . 

 Strophonella striata Hall . . 

 Strophonella semifasciala Hall . 

 Pleclambonites transversalis Dalman 

 Mimulus wcddronensis Millei' and Dyer 

 Choneles nova-scoiicus Hall . 

 Chonetes undulatus Hall 

 Dictyonella reticulata Hall . 

 Clorinda fornicata, var., Hall 

 Anastrophia internascens Hall 

 Camarotoechia neglecta Hall 

 Ca/narotoechia acinus Hall . 

 Camarotoechia indianensis Hall 

 Camarotoechia Whitii Hall . 

 Uncinulus Stricklandi Sowerby 



Rhyiichotreta cuneata Dalman . 

 Atrypa reticularis Linntcus 

 Zygospira minima Hall . 

 Atrypina disparilis Hall 

 Homceospira evax Hall . 

 Homoeospira sobrina sp. n 

 Nucleospira jrisiformis Hall * 

 Meristina rectirostris Hall 

 Whitjieldella nit id a Hall 

 Meristina Maria Hall 



Spirifer eudora Hall . 

 Spirifer crispus Hisinger 

 Spirifer crispus, var. simplex, Hall 

 Spirifer rndiatus Sowerby 

 Reticularia bicostnta, var. petila, Hall 



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

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

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



No young shells obtained. 

 Numerous inchoate specimens. 

 No young shells obtained. 



u a (1 



a (( (( 



Full series showing development. 



U (( u 



No young shells obtained. 



Full series, showing development. 



No young shells obtained. 



One embryo. 



No young shells obtained. 



Li. U 1 1 



Young shells not rare. 

 No young shells obtained. 

 Young shells not rare. 

 Young shells very abundant. 



Mature form abundant ; no young 



shells obtained. 

 Young shells common. 

 Young shells abundant. 

 No young shells obtained. 

 Young shells common. 

 Young shells very abundant. 

 Young shells not rare. 



(( u a 



Full series, showing development. 

 Numerous inchoate specimens. 

 Incomplete series showing devel- 

 opment. 

 No young shells obtained. 

 Full series, showing development. 



