1366 



THE VOYAGE OF H.M.S. CHALLENGER. 



These apophyses exhibit a remarkal)le variety in the great subfamily Theophormida, with 

 open mouth. In the small subfamily Theophaenida, however, the apophyses appear as 

 six or nine simple lateral wings on the abdomen. 



The Theophormida are richly represented not only in the present seas, but also as 

 fossils in Barbados, and numerous remarkable forms have been already described by 

 Ehrenberg, in his genera Calocyclas and Cydadophora. Many Phormocyrtida belong- 

 to the most elegant and admirable forms of Eadiolaria. 



Synopsis of the Ge7iera of Phormocyrtida. 



I. Subfamily 



Theophormida. 

 Terminal mouth of the 

 abdomeQ a simple 

 wide opening. 



Radial ribs 



enclosed in 



the wall of 



the shell, 



either the 



thorax 



or the 



abdomen. 



No radial 

 ribs in the 

 sliell-wall. 

 Peristome 



with a 



corona of 



terminal 



feet. 



Radial ribs in 



the thorax and 



the abdomen. 



Radial ribs in 



the abdomen 



only. 



Terminal 

 corona simple. 



Corona of feet 

 double. 



Abdomen flat, dilated, with 

 a wide open mouth, 



Abdomen ovate or cylin- 

 drical, with constricted 

 mouth, . 



Peristome with free ter- 

 minal feet. 



Peristome smooth, without 

 free feet, 



f Abdomen cylindrical or 

 I ovate, not dilated, 



Abdomen dilated, truncate, 

 conical or disooidal, 



[ Both coronas terminal. 



One corona terminal, the 

 other lumbar, 



II. Subfamily 



Theophfenida. 



C Terminal mouth of the ab- ( Six lateral wings, . 



■; domen closed by a lattice- < 



( plate. ( Nine lateral wings, . 



601. Theophormis. 



602. Phormocyrtis. 



603. Alaeorys. 



604. Cydadoj^Jwra. 



605. Calocyclas. 



606. Clafhrocyclas. 



607. Lamproeyclas. 



608. Diplocyclas. 



609. Hexalatractus. 



610. Theophama. 



Subfamily 1. Theophormida, Haeckel, 1881, Prodromus, p. 436. 



Defi7iition. — P h o r m o c y r t i d a with the basal mouth of the shell open (vel 

 Tricyrtida multiradiata aperta). 



Genus 601. Theophormis,^ Haeckel, 1881, Prodromus, p. 436. 



Definition. — T h e o p h o r m i d a (vel Tricyrtida multiradiata aperta) with numerous 

 radial ribs enclosed in the wall of the thorax and of the flat dilated abdomen ; mouth 

 of the latter wide open. 



' Theophormis = T)\\mt bastet ; dto;, <poj^;f. 



