APPENDIX. 429 



757. AcTiNOCYCLUs nonariiis. — Partitions not present, 

 disc having nine finely punctated rays. This species is 

 found, both fossil and alive, in the same situation. The 

 single discs of the fossil forms are generally without mar- 

 gin : they are sometimes quite perfect, but often in 

 broken pieces. In the living creatures, the ova are 

 yellow; locomotion not observable. Diameter 1 -720th 

 to l-650th. 



758. AcTiNOCYCLUS denarius. (1838.) — Found fossil 

 in the chalk marl of Oran; and living, in the waters of the 

 Cattegat. 



759. AcTiNOCYCLUS undenarius. — Partitions not present, 

 disc having eleven finely punctated rays. This species is 

 found, both alive and in the fossil state, where the pre- 

 ceding one is seen. The discs of the fossil forms are 

 destitute of margin, and are single, whilst those of the 

 live creatures have a broad edge and are double. In 

 those specimens in which the margin is absent there exists 

 as many round openings as there are punctated rays. 

 The mass of ova is divided into several portions. Diameter 

 of the discs l-560th to l-480th. 



760. ACTINOCYCLUS bisenarius. — Partitions not present, 

 disc having twelve finely punctated rays. Found fossil 

 in the chalk marl of Oran, and alive in the water of the 

 Cattegat. The twelve rayed discs of the fossil forms are 

 sometimes smaller than those of the living, but, in most 

 cases, about equal. In the live condition, the ova are 

 visible, as twenty-two greenish masses placed around the 

 colourless spot in the centre of the body. Neither marginal 

 openings or locomotion have been satisfactorily seen. 

 Diameter of the fossil, as low as l-860th; of the living, as 

 high as 1 -580th. 



761. ACTINOCYCLUS duodenarius. — Disc divided inter- 

 nally, by partitions, into twelve cells, and having twelve 

 finely punctated rays; six dark and six bright triangular 



