for the Microscope. 39 



In this genus the shape is also circular or discoid, and the 

 markings of the valves consist of radiating dots (granules) 

 nearly reaching a small central blank space. Near the 

 margin, a small circular clear portion has the appearance 

 of a nodule. This species is easily distinguished by its 

 beautiful blue colour when mounted in balsam and viewed 

 under a low power. Found in the stomachs of molluscs 

 and in dredgings. (PL IV., fig., 29.) 



278. TRANSPARENT ACTINOCYCLUS (Actinocyclus subtilis) 

 is very transparent, with numerous radiating dotted lines. 

 Found in the same localities as the foregoing. 



279. WAVED ACTINOPTYCHUS (Actinoptyehus undulatus). 

 The species which compose this genus are distinguished 

 by the division of the disc into triangular portions by 

 radiating lines. In the present species the segments are 

 alternately elevated and depressed. Found in the stomachs 

 of molluscs and in dredgings. (PL IV., fig. 14.) 



280. MANY-EYED EUPODISCUS (Eupodiscus argus). 

 The present genus differs from Coscinodiscus, in the struc- 

 ture being apparently less cellular, and in the raised pro- 

 cesses or horns which occur on the margin of the disc, 

 of which this species has three or more. Found at the 

 mouths of rivers and in dredgings. (PL IV., fig. 13.) . 



281. TWIN-SPOT AULISCUS (Auliscus sculptus). In this 

 genus also the forms are discoid or oval, with two circular 

 flattened processes at some distance from the margin in 

 each valve. The present is the only British species, and 

 occurs in the mud at the mouths of rivers and in dredgings. 

 (PL IV., fig. 15.) 



282. EARED BIDDULPHIA (Biddulphia aurita}. The 

 large, angular, four-sided frustules in this genus adhere to 

 each other in a chain by their alternate angles. The vaive 

 in this species is elliptical, with two or three spines in 

 the central elevation. Common on Algae. (PL IV., 



fig- 23.) 



283. HONEYCOMBED TRICERATIUM (Triceratium favus). 

 The side view in the species of this genus is either three, 

 four, or five angled. In the present the cells are long 

 and hexagonal, the sides nearly straight, or a little convex 



