454 



ANAULUS. 



Three forms inhabiting Asiatic tropical seas are included in the genus 

 Hydrosera, one of which, H. Whampoense Sclav., has also been found in a 

 fossil state in Hungary by Dr. Pantocsek. 



The best known species usually found in collections is H. triquetra Wall., 

 which is represented in the text (fig. 178). 



GENUS 119. ANAULUS (Ehr., 1844), Char, emend. 



Frustule simple,with girdle 

 face subquadrangular, fur- 

 nished with costae transverse 

 or scalariform, not capitate : 

 connecting zone smooth or 

 finely striate. Valve oblong, 

 often lunate, with margins 

 straight or undulate. 



Fig. 179. Anaulus birostratus. 

 a., c. Valve view. b. Girdle view. 



I divide this genus into the subgenera Eu-Anaulus and Eunotogramma 

 And., the latter being distinguished by the form of the valve being lunate (more 

 or less crescent-shaped). 



No true Anaulus (there are about a dozen species) has hitherto been 

 found in our regions ; they are found either fossil or living in the torrid or 

 Arctic regions. Such is Anaulus birostratus Grun. (fig. 179), which has been 

 found in California, Peru, Oamaru, the Balearic Islands, &c. 



As to Ennotogramma (fig. i3o = E. laevis 

 Grun.), of which about a dozen species have been 

 described, the following has been found in 



Belgium :- 



a. b. 



Fig. 180. Eunotogramma Icevis. 

 a. Valve view, c. Girdle view. 



A. debilis (Grun.) H. Van. Heurck {Eunotogramma Grun., 

 H.V.H. Atl., pi. 126. f. 17-19*), plate 34, fig. 892 ; plate 19, fig. 626. 



