EEPOET ON THE RADIOLARIA. 



1135 



I. Subfamily 



Archipilida. 

 Basal mouth of the - 

 shell a simple 

 wide opening. 



II. Subfamily 



Archiperida. 

 Basal mouth of the 



shell closed by a 



lattice-plate. 



Synopsis of the Genera of Tripocalpida 



Three terminal feet. 



Shell with three 



lateral ribs or 

 wiiiys, with or 

 without ter- 

 minal feet. 



Shell without 

 lateral ribs or 

 wings but with 

 three terminal 

 feet. 



Shell in its axis 

 with a free (simple 

 or branched) in- 

 ternal columella, 

 prolonged into an 

 apical horn. 



( Apex with a horn, . 

 ( No apical horn. 



Six to nine or more I -kj -it, 

 , ■ , X i. !■ No apical horn, 



terminal feet. I ^ 



No terminal feet. 



Apex with a horn, 

 No apical horn, 



Feet simple or ] Apex with a horn, . 

 branched, not lat^ 



ticed. 



Feet latticed. 



Shell with three 

 free feet, without 

 lateral lattice- 

 wings. 



Shell with three 



lateral lattice- 

 wings, connecting 

 the three feet with 

 the horn. 



Shell with simple cavity, without free 

 columella. Three free basal feet. 



No apical horn. 

 Apex with a horn, . 



Columella simple, . 

 Columella branched, 



Columella simple, . 

 Columellabranched, 



One apical horn. 

 Two or more horns. 

 No apical horn. 



496. Tripoealpis. 



497. Tripodoniiim. 



498. Tripterocalpis. 



499. Trissopilium. 



500. ArcMpilium. 



501. Tripilidium. 



502. Tripodiseium. 



503. Tridictyopus. 



504. Euscenium. 



505. Cladoseenium. 



506. Archiscenium. 



507. Pteroseenium. 



508. Peridium. 



509. Archipera. 



510. Archiburm. 



Subfomil)" 1. Aechipilida, Haeckel, 1881, Prodromus, p. 427. 



Definition. — T r i p o c a 1 p i d a with the basal mouth of the shell open (vel Mono- 

 cyrtida trii-adiata aperta). 



Genus 496. Tripocalpis,^ Haeckel, 1881, Prodromus, p. 428. 



Definition. — A r c h i p i 1 i d a (vel Monocyrtida triradiata aperta) with three lateral 

 ribs prolonged into three terminal feet. Apex with a horn. 



The genus Tripocalpis opens the series of Archipilida, or of those Monocyrtida in 

 which the monothalamous shell exhibits a distinct triradial structure, and a simple open 

 mouth, without cortinar lattice. Tripocalpis is probably the most primordial of the 

 Archipilida, and has three lateral ribs, which are prolonged into three free terminal 



I Tripocalpis = \]td. with three feet ; tjiVoi/;, x«>nr/V. 



