SCHUCHERT.] 



KEY TO BRACHIOPOD FAMILIES. 



137 



SynopsiH of the divisions of Brachiopoda higher than (/entrrt— Coutiiiueil 

 Siiperorders. Orders. Superfamilue. 



Pedicle restrict- 

 ed to ventral 

 A'iilve through- 

 out life or only 

 in youthful 

 growth. (Idi- 

 ocaulia.) 



Pedicle aper- 

 ture modified 

 hy a deltidi- 

 Pediclo restrict- uni. (Acro- 

 ed to ven- tretacea. 

 trai valve 

 t li rimgliout J P ed icle slit 



life. Inartii' 

 iilalc. (Ne<i 

 Iremala.) 



moditied by 

 a 1 is t riuni. 

 (I)i.sciuacea. ) 



Pedicle sui»- 

 pressed. (Cra- 

 uiacea.) 



Pediclorestrict- 

 ed to ven- 

 tral valve 

 throughout 

 or a portion 

 of life. Artic- 

 ulate. (Pro- 

 tremata.) 



Shells without 

 spondyliaand 

 c r 11 r a 1 i a . 

 (Strophomen- 

 acea.) 



Shells with 

 spondylia and 

 cruralia. 

 (Peutamera- 

 oca.) 



Fainiliex. 

 Pedicle opening small, cir- 

 cular, posterior to pro- 

 tcgnlum — Acrotretida'. 



I'ediclo lissurt! narrow, 

 elongate, anterior to pro- 

 tegulum — Siphonotretidw. 



Pedicle fissure marginal, 



ojien posteriorly - Trematida;. 



Pedicle fissure narrow, 

 elongate, closed posteri- 

 orly --- Piscinidw. 

 Shells partially or com- 

 pletely cemented to for- 

 eign bodies = Craniidae. 

 Pedicle opening large; del- 

 tidium and articulation 

 incipient. No crural 

 process = Katorginidae. 

 Rostrate, aberrant Stro- 



phonienacea = Eichwaldiidae. 



Cardinal areas and deltid- 

 iuni well developed. No 

 cardinal process = Billingsellids. 



Cardinal areas, deltidiuni, 

 chilidiuni, asd cardinal 

 process well developed — Strophomenidse. 

 Strophomenid» with im- 

 pressed brachial furrows — Thecidiidie. 

 Valves more or less cov- 

 ered with hollow, anchor- 

 ing spines = Productid<e. 

 Cone-shaped productoids 

 completely modified hy 

 cementation = Richthofenidse. 

 Delthyrium usually large, 

 open ; deltidium devel- 

 oped only in early 

 growth ~ Orthidas. 

 Large, straigh t cardinal 

 areas with prominent 

 deltidium. No cruralia -.— Clitambonitidae. 

 Straight cardinal areas, 

 prominent deltidium, 

 and short cruralia = Syntrophiidae. 

 Shells intermediate in 

 structure between Syn- 

 trophiida' and Penta- 

 meridaj ^= Porambonitidte. 

 Shells rostrate, commonly 

 without deltidium. Cru- 

 ralia well developed — Peutameridae. 



