ORDER IV 



TELOTREMATA 



333 



The lower genera become 



i, Mill/a*, Muyasella, Tcrebratetta, muf Magellania. 



in/ lilt Iff or*' i-nl fit! HI/ fill' tr nit illil I 



stages. Jura to Recent. Recent 

 genera restricted to austral seas. 



ouchardia, Davidson (/W///- 

 i'h i/iii'li us, King). Recent; South 

 Atlantic. 



Nijas, Sowerby (Fig. 565). 

 Cretaceous; Europe. J/tfy ><//", 

 Dall. Recent. Coenothyris, 

 Douville" (Fig. 566). Trias. 



Terebratella, d'Orbigny (Del- 

 fhi/ris, Menke ; Ismenia, King ; 

 WaltoMO, Davidson), (Fig. 567). 

 Jura to Recent. 



Minjellania, Bayle (IVald- 

 heimia, King; Neothyris, Dou- 

 ville), (Fig. 568, also Figs. 

 497, 498). Jura to Recent. 



JHtf/nch&rina, Oehlert. Cretaceous. Megerlina, Deslongchamps. Recent. 

 Kraussina, Davidson (Kraussia, Davidson). Recent. Mannia, Dewalque. 

 Miocene. 1 Rhynchora, Dalman. Cretaceous. 



FIG. 568. 



.M<><l<:U<tniafl(n-escens, Val. Recent ; 

 Australia. Interior of dorsal valve, 

 somewhat enlarged. 



Superfamily 3. SPIRIFERACEA. Waagen. 



Telotremata with the adult brachia supported by calcareous spiral lamellae or 

 spiralia. Ordovician to Jurassic. 



The Spiriferacea are abundantly represented from the Silurian to the Carboniferous, 

 during which time the jugum undergoes many and often rapid changes. The brachidia 

 in Zygospira are known to begin with a Centronella-like loop, as in the primitive Tcre- 

 bratulaceck 



Family 1. Atrypidae. Gill. 



Spiriferacea with the crura directly continuous with the primary lamellae, which 

 diverge widely and have the spiral cones between ///////. 

 Jugum simple, complete, or incomplete. Ordovician 

 to Devonian. 



This family is divided into Zygospirinae, 

 and Atrypinae, according to modifications of the jugum 

 or position of the spirals. 



Zygospira, Hall (Anazyga, Davidson ; OrtJunm- 

 maea, Hall ; Hallina, Winchell and Schuchert ; 

 Protozyga, Hall and Clarke (Fig. 569). Like 

 Atrypa, but small, and the spirals composed of 

 fewer coils. Jugum a simple connecting band, 

 situated rather anteriorly. Surface sharply 

 plicate, never lamellose. Ordovician and Sil- 

 urian ; North America. 

 Catazyga, Hall and Clarke. More rotund and finely striated than Zygospira. 



FIG. 569. 



Zygospira modest a, Hall. Ordovician 

 Cincinnati, Ohio. /i (after Hall). 



