116 On the Microscopical Siliceous Polycystina of Barbados, 



scribed previous to Ehrenberg's examination of the Barbados 

 rocks consisted of thirty-nine species, including five genera, 

 which were partly found in a fossil state in rocks of different ages, 

 and partly existed in living forms in the North Sea, and at the 

 bottom of the sea near the South Pole. The discovery of so 

 many additional forms has enabled him to class the Polycystina 

 under fifteen genera, all of which occur in the rocks of Barbados 

 in numerous species. The species previously known are now 

 named as follows : — 



Cornutella Cassis 



clathrata 

 Lithocampe 

 obtusa 

 Flustrella bilobata (Lagena) 

 concentrica 

 limbata 

 pretext* 

 spiralis 

 Lithobotrys cribrosa 



denticulata 

 Galea 

 quadriloba 

 triloba 

 Lithosambe antarctica 

 aculeata 

 acuminata 

 aurita 

 Auricula 

 australis 

 Hirundo 

 lineata 

 punctata 

 Radicula 

 solitaria 

 stiligera 

 Haliomma Amphisipfoon 

 JEquorea 

 (cornutum 

 crenatum 

 didymum 

 dixipbos 

 (Lagena [Flustrella] 

 Medusa 

 nobile 

 oblongum 

 ovatum 

 radians 

 (radiatum) 

 radicatum 

 Sol 



: Cornutella Cassis. 

 : clathrata. 



: Eucyrtidium Lithocampe. 

 : Lophopha?na ? obtusa. 

 : Rhopalastrum lagenosum. 

 : Flustrella concentrica. 

 : Perichlamydium limbatum. 

 prsetextum . 

 : Flustrella spiralis. 

 Lithobotrys cribrosa & triloba. 

 Li th opera denticulata. 

 Lithocorythium Galea. 

 Lithobotrys quadriloba. 

 triloba. 

 : Eucyrtidium antarcticum. 

 Pterocanium aculeatum. 

 Eucyrtidium acuminatum, 

 auritum. 

 auritum ? 

 australe. 

 Lithornithium ? Hirundo. 

 Eucyrtidium lineatum. 



punctatum. 

 Lithocampe Radicula. 

 Carpocanium solitarium. 

 Eucyrtidium ? stiligerum. 

 Astromma? Entomocora. 

 Haliomma iEquorea. 

 Caryolithis crenata) . 

 Haliomma crenatum. 

 Astromma Entomocora? 

 Haliomma dixiphos. 

 Rhopalastrum lagenosum). 

 Haliomma Medusa, 

 nobile. 

 oblongum. 

 ovatum. 

 radians. 



Ceratospyris radicata. 

 Haliomma Sol. 



As long as a few forms only of this peculiar group were 

 known, it was not difficult to assign to them a place in our ex- 

 isting classification : it is however different at present, when 

 Ehrenberg describes nearly 300 species — a larger number of spe- 



