REPORT ON THE RADIOLARIA. 



1179 



Prodromus, comprises those Cyrtoidea in which the lattice-shell is quite simple, with- 

 out transverse constriction, and without radial apophyses. The two subfamilies differ in 

 the shape of the basal mouth, which in the Archicorida is a simple wide opening, but in 

 the Archicapsida is closed by a lattice-plate. 



Only a few species of this family were formerly known. Ehrenberg, in 1838, founded 

 upon these the genus Cornutella, one of the three oldest genera of Polycystina 

 (Cornutella, Lithocampe, Haliomma). In 1862 I described some living forms, with 

 a central capsule, as Cyrtocalpis. The Challenger collection contains a large number of 

 new genera and species. 



Probably the family Cyrtocalpida is an artificial group, comprising two or more 

 different subfamilies of very different origin. The Cornutellida (Cornutella, Cornu- 

 tanna) have probably been derived from the Sethocorida by loss of the cephalis, so that 

 their conical shell represents a thorax alone. The Mitrocalpida on the other hand 

 (genera 528531) may be originally simple ovate shells (like Gromia and Lecythium), 

 arising independently from the Nassellida. The Archicapsida (Halicapsa, Archicapsa) 

 are probably derived from the Zygospyrida (Dictyospyris, Circospyris) by loss of the 

 sagittal ring and constriction. This is nearly certain, when the three or four typical 

 cortinar pores appear in their basal plate. Some forms of Halicapsa, may be easily 

 confounded with some forms of Prunoidea (Lithapium). 



Those Cyrtocalpida, which possess a central capsule with three or four lobes, are 

 probably derived from Tripocyrticla by loss of the three feet, or from Sethocyrtida by 

 loss of the cephalis, since the lobes indicate the original presence of cortinar pores and 

 of a cephalis. Those Cyrtocalpida, however, in which a simple ovate shell encloses a 

 simple central capsule without lobes, may be original " Monocyrtida eradiata," without 

 relation to any radial ancestral forms. 



I. Subfamily 



Archicorida. 

 Basal mouth of the J 

 shell a simple wide 

 opening. 



Synopsis of the Genera of Cyrtocalpida. 



Shell conical, gradu- ( With horn, 



ally dilated to < 



Shell with simple wards the mouth. ( No horn, 

 lattice-work (not { 

 double or spongy). I Shell ovate or urceo- ( With horn, 



late, with con- -j 

 [ stricted mouth. ( No horn, 



f Shell ovate, double, with an external 



, mantle, .... 



Shell not simply J 



Shell ovate, with spongy irregular lattice- 

 work, .... 



latticed. 



[ 



Shell with an apical horn, 



II. Subfamily 



Archicapsida. 

 Mouth closed by a tot- 1 gl n without hom Qn the 

 tice plate. 



526. Cornutella. 



527. Cornutanna. 



528. Arehicorys. 



529. Cyrtocalpis. 



530. Mitrocalpis. 



531. Spongocyrlix. 



532. Halicapfa. 



533. Archicapsa. 



