OSTRACODA. 379 



Cythere thompsoni, n. sp. Plate II., figs. 15 and 16. 



Shell seen from the side oblong, subquadrangular, height rather more than half 

 the length ; anterior extremity wide and obliquely rounded, with about a dozen short 

 thick teeth, posterior slightly narrower, almost truncate, with five or six short stout 

 teeth ; dorsal margin deeply sinuated in the middle, highest at the anterior end, 

 ventral margin slightly sinuated near the anterior end ; seen from above broadly 

 ovate, with irregular outline, width rather more than half the length, widest near the 

 posterior end ; anterior extremity obtuse, with two mucronate processes, posterior 

 wide, truncated, with broad, tooth-like median projections ; surface of the shell 

 marked with large regular ridges and deep depressions, which become very conspicuous 

 in dead shells; size, 073 millim. 



In the general washings and in washings from Gulf of Manaar sponges. 



This well-marked species is named in memory of my friend and fellow-worker, the 

 late Mr. ISAAC C. THOMPSON, F.L.S., who was jointly responsible with me in the 

 preparation of the " Report on the Copepoda," published in the first volume of this 

 work. 



Cythere donnani, n. sp. Plate II., figs. 17 and 18. 



Shell seen from the side subsigmoid, height equal to half the length ; anterior 

 extremity wide and very obliquely rounded, with about fourteen small teeth on the 

 lower margin, posterior narrow, slightly produced in the centre, with four small teeth 

 below the middle ; dorsal margin sinuated in the middle, highest at the anterior and 

 rounded off towards the posterior, ventral sinuated. convex in front and behind ; seen 

 from above broadly ovate, width slightly less than half the length, with rounded 

 extremities, slightly produced into thickened lips, widest near the posterior, and 

 slightly sinuated in the middle ; surface of the shell marked with a number of fairly 

 regular longitudinal ridges and rows of impressed puncta ; size, 0'98 millim. 



In washings from Cheval pearl oysters, and from Gulf of Manaar sponges. 



Named after Captain DONNAN, Inspector of the Pearl Banks in 1902. 



Cythere willeyi, n. sp. Plate II., figs. 19 and 20. 



Shell seen from the side oblong, subquadrangular, height equal to rather more than 

 half the length ; anterior extremity wide and very obliquely rounded, with about 

 seventeen short stout teeth, posterior much narrower, bluntly rounded, with four 

 short teeth on the lower margin ; dorsal margin very slightly sinuated in the middle, 

 highest in front, and rounding off posteriorly, ventral sinuated slightly in front of 

 the middle ; seen from above broadly ovate, with irregular outline, width rather 

 more than half the length, widest in front of the middle ; anterior extremity obtuse, 

 with two mucronate processes, posterior widely triangular ; surface of the shell 

 marked with large irregular puncta, and a distinct dorsal ridge ; size, 0'8 millim. 



In general washings from Gulf of Manaar. 



Named after Dr. ARTHUR WILLEY, Director of the Museum at Colombo. 



3 c 2 



