380 CEYLON PEARL OYSTER REPORT. 



Cythere hornelli, n. sp. Plate II., figs. 21 and 22. 



Shell seen from the side siliquose, height rather less than half the length ; anterior 

 extremities narrowed and rounded, smooth ; dorsal margin boldly arched, highest in 

 the centre, ventral sinuated in the middle ; seen from above wedge-shaped, width less 

 than half the length, widest near the posterior ; anterior extremity produced, with two 

 mucronate processes, posterior margins truncate, and produced into a bi'oad triangular 

 projection ; surface of the shell marked with a number of curved ridges and rows of 

 impressed puncta ; size, - 53 millim. 



In general washings from invertebrata from Gulf of Manaar. Named after 

 Mr. James Hornell, now Inspector of the Pearl Banks. 



Cythere halyi, n. sp. -Plate II., figs. 23 and 24. 



Shell seen from the side oblong, quadrangular, height slightly less than half the 

 length, widest in the middle ; anterior extremity broadly rounded, with one tooth 

 below the centre ; posterior produced into a wide triangular beak ; dorsal margin flat, 

 with a corrugated margin, highest at the extremities, ventral slightly convex and 

 irregular ; seen from above narrowly ovate, with produced and thickened extremities, 

 widest behind the middle, width considerably less than half the length ; surface of 

 the shell marked with numerous impressed puncta and studded with bluntly pointed 

 spines ; size, 0"55 millim. 



In general washings from invertebrata from Gulf ot Manaar. Named after 

 Mr. Haly, a former Director of the Colombo Museum. 



Cythere kelaarti, n. sp. Plate II., figs. 25 and 26. 



Shell seen from the side oblong, subquadrangular, height scarcely equal to half 

 the length ; anterior extremity broadly and obliquely rounded, with about 21 short, 

 stout teeth ; posterior narrow and subtruncate, with seven short, thick spines ; 

 dorsal margin slightly sinuated, highest in front and sloping gently backwards, ventral 

 nearly straight, much contracted at the posterior ; seen from above doubly triangular, 

 widest much behind the middle, where the outline is produced into a blunt tooth ; 

 width slightly more than half the length ; anterior extremity with two, and the 

 posterior with four, spines ; surface of the shell marked with numerous impressed 

 puncta, very rough and studded with short, aculeate spines, one triangular tooth near 

 the posterior; size, 0'65 millim. 



In general washings from dredged invertebrates from Gulf of Manaar. Named 

 after Dr. Kelaart, who investigated the pearl banks in 1857. 



Cythere willisi, n. sp. Plate II., figs. 27 and 28. 



Shell seen from the side subquadrangular, with compressed margins, height slightly 

 less than two-thirds of the length ; anterior extremity broad and very obliquely rounded, 



