256 
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 tew, 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. (PI. XVIII. f. 7-9.) 
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 wdiole length, and a smaller similar ridge is seen near 
the ventral margin. 
Hab. Tenedos. Mr. Williamson’s collection. 
3. Cythereis fistulosa, Baird. (PI. XVIII. f. 1-3.) 
Carapace valves nearly quadrilateral, elongate. Anterior extremity 
a little more rounded than posterior, and armed with seven or eight 
small teeth; posterior extremity armed with five or six larger teeth. 
Dorsal and ventral margins nearly straight. Surface of valves gra¬ 
nular and ornamented by four elevated straight ridges, which are per¬ 
forated near their margins with small round holes. 
Hab. Manilla. Mr. Williamson s collection. 
4. Cythereis praya, Baird. (PI. XVIII. f. 13-15.) 
Carapace valves sub quadrangular. Anterior extremity considerably 
broader than posterior, rounded, smooth round the edge, and having 
a broad flat margin beset on inner edge ’with small round tubercles ; 
posterior extremity emarginate, and furnished on inferior halt with 
several short teeth. Valves extremely gibbous in centre, and the 
surface very rough, wrinkled, and tubercled. 
Hab. Tenedos. Mr. Williamson’s collection. 
5. Cythereis deformis, Baird. (PI. XA III. f. 4-6.) 
Carapace valves ovate, short and gibbous; the two extremities of 
nearly the same size. Dorsal and ventral margins nearly straight. 
Surface of valves very coarsely granulated and tubercled; roughly 
ridged, but the ridges not perforated as in the preceding species. 
Hab. Manilla. Mr. Williamson’s collection. 
6. Cythereis senticosa, Baird. (PI. XVIII. f. 16-18.) 
Carapace valves flat, ovate. Anterior extremity broader than poste¬ 
rior, and rounded. Dorsal margin sloping towards posterior extre- 
