Zoological Society. 57 



straight ; ventral slightly sinuated in the centre. Anterior and poste- 

 rior extremities of nearly equal size. Surface of valves smooth and 

 shining, and of a dull white colour. 



This species resembles in shape the Candona reptansy but is only 

 about one-fourth the size, and is of a uniform dull white colour. 



Hab. Freshwater pond at Charing, Kent ; collected by W. Harris, 

 Esq., to whom I am indebted for specimens. Regent's Park (T. Ru- 

 pert Jonesy Esq.). 



Genus CytAere, Miiller. 



1 . Cythere Tarentina, Baird. 



Carapace valves obovate. Anterior extremity much broader than 

 posterior, and having a broad flat margin striated on the surface 

 and toothed round the edge ; posterior extremity pointed, having the 

 same margin, but not so broad, and with much fewer teeth. The 

 valves are very convex in the middle, of a greyish colour, with a 

 white patch in the centre, and are slightly pitted all over. Dorsal 

 and ventral margins both somewhat prominent. 



Hab. Tarentum. In Mr. Williamson's collection. 



2. Cythere setosa, Baird. 



Carapace valves oval. Anterior extremity narrower than poste- 

 rior. Dorsal margin arched ; ventral sinuated about its anterior third. 

 Surface of valves shining white, and studded all over with short stiff 

 hairs. 



Hab. Moreton Bay, Australia, and Tenedos. Mr. Williamson's 

 collection. 



Genus Cythereis, Jones. 



1. Cythereis australis, Baird. 



Carapace valves somewhat quadrilateral. Dorsal and ventral mar- 

 gins nearly straight. Anterior extremity broader than posterior, and 

 finely toothed ; teeth numerous. Posterior extremity emarginate on 

 upper or dorsal edge, and toothed on ventral ; teeth few, and stronger 

 than those on anterior margin. Surface of valves roughened with 

 small asperities, and having one tubercle on about the anterior third 

 of its length. A raised margin encircles the whole valve. 



Approaches very near Cypridina hieroglyphica of Bosquet, Ento- 

 most. Maestricht, t. 3. f. 4. 



Hab. Moreton Bay, Australia. Mr. Williamson's collection. 



2. Cythereis runcinata, Baird. 



Carapace valves ovate, flat. Anterior extremity broader than poste- 

 rior, and rounded ; posterior extremity emarginate on upper or dor- 

 sal margin. Surface of valves very flat and rugose ; a flat projecting 

 border surrounds each valve, which is serrulated at anterior extremity 

 and toothed on posterior ; a high raised sharp ridge runs across the 

 centre of the valve somewhat in a diagonal direction, which is serru- 

 lated along its whole length, and a smaller similar ridge is seen near 

 the ventral margin. 



Hah. Tenedos. Mr. Williamson's collection. 



