2?2 DISCOVERY REPORTS 



and A. octonarius. Later, other forms were added, and Ehrenberg, realizing that the 

 genus contained more than one group, desired to make a separation. Ehrenberg 18400, 

 introduced a subgenus in the following manner : 



" Actinocyclus (Actinoptychus) senarius, synonym Actinocyclus senarius 1838." Later 

 Ehrenberg ((1841) 1843, p. 400) established the genus Actinoptychus. On a previous 

 page (p. 328), and in the description of the plates, the combination Actinoptychus 

 senarius was used, and there is reason to believe from the similarity of the figures pro- 

 vided that Actinoptychus senarius Ehrenberg was based on Actinocyclus senarius (1838). 

 Ehrenberg (1843, p. 400) explained that the separation was necessary on account of 

 structural differences that existed in Actinocyclus (1838) and continued at some length 

 to explain the differences upon which the separation was made. Actinocyclus octonarius 

 Ehrenberg (1838) was retained as the type species of Actinocyclus. The species Actino- 

 ptychus senarius is often attributed to Bailey in the following manner "Actinoptychus 

 undulatus Bailey", but there appear to be no grounds for this. Bailey (1842) mentioned 

 the occurrence of a number of species of Actinocyclus in fossil material from Richmond, 

 Virginia, and provided figures which undoubtedly represented the species under con- 

 sideration here, but the figures were unnamed. Ehrenberg (1843, p. 328) accepted 

 Bailey's figure as being equal to his Actinoptychus senarius. Kiitzing (1844) took 

 Bailey's illustration as a type illustration and described Actinocyclus undulatus. Ralfs 

 (1861) placed this species in the genus Actinoptychus, but accepted Kiitzing's epithet. 

 Ehrenberg's epithet is used here to satisfy the claims of priority. 



Observed at Sts. 260, 261,262, 263,482, 719, 721, 1359; WS 100, 101, 103, 104, 105, 

 106, 107. 



Actinoptychus splendens (Shadbolt) Ralfs ex Pritchard. 



Pritchard, 1861, p. 840. 

 Hustedt, 1929, p. 478, fig. 265. 

 Actinosphaenia splendens Shadbolt, 1854, p. 16. 



Cells discoid. Valve divided into sectors alternately raised and depressed. The number 

 of the sectors varies considerably, but is usually sixteen, eighteen or twenty. Central 

 area present, area almost circular. Sectors covered with coarse areolation. Areoles 

 polygonal, furnished with secondary structure upon the inner wall. Adjoining sectors 

 have different structure. On the one is a stout apicule placed at the margin of the valve ; 

 from the apicule proceeds radially a narrower hyaline line to the central area. The other 

 sector is shorter, and does not join the margin, but leaves a narrow hyaline space at the 

 broad or marginal end ; also it seldom encroaches upon the central area to the same 

 degree as the other sector, giving to the central area a stellate appearance. The valve is 

 surrounded by a strong striate outer margin. Chromatophores : numerous plate-like 

 bodies. Diameter of valve 1 20-1 40/x. 



Probably an oceanic species, observed but rarely off the coast of South Africa. 



Observed at St. 260. 



