226 CEYLON PEAEL OYSTER REPORT. 



tudinallv and give off short branches also containing broken spicules into the 

 surface conuli. The secondaries are arranged as in the basal crust. 



The flagellate chambers are very small, only about 0"024 millim. in diameter, and 

 approximately spherical, but the arrangement of the collared cells, on the inhalant 

 side of the chamber only, gives them a curious crescentic appearance ; moreover, they 

 frequently appear in sections to be arranged in single curved rows ; surrounding the 

 narrow exhalant canals at about equal distances, and doubtless communicating with 

 them by very long and narrow canaliculi, but the condition of the specimen is not 

 good enough to enable me to make out minute histological details. The ectosome is 

 chondrenchymatous rather than collenchymatous, but a large quantity of gelatinous 

 tissue is developed around the larger canals in the choanosome. In the neighbourhood 

 of the flagellate chambers the choanosome is abundantly granular, and both ectosome 

 and choanosome contain numerous pigment cells. 



It affords me much pleasure to name this well-characterised species after Professor 

 W. A. Herdman. 



K.N. 340 (Ceylon seas). 



Class: CALCAPEA. 

 Porifera with a skeleton composed of calcareous spicules. 



The number of calcareous sponges in the collection is remarkably small, only four 

 species being represented, two of winch, however, are new. I have discussed the 

 classification of the group in considerable detail in my earlier writings (76, 78, 80) and 

 adhere to the opinions therein expressed. 



Order 1 : HOMOCCELA. 

 ( Calcareous sponges in which the endoderm consists throughout of collared cells. 



Leucosolenia, Bowerbank. 

 With the characters of the order. 



Leucosolenia (Clathrina) coriacea (Montagu), var. ceylonensis, nov. Plate XIII. , 

 fig. 8. 



[For literature and synonyms vide Haeckel (7)]. 



This well-known European species is represented in the collection by a slight 

 variety belonging to the reticulate section of the genus Leucosolenia as defined by 

 the present writer (76). The sponge forms massive, closely reticulate colonies of 

 slender ascon-tubes, each colony with a constricted base of attachment ; with fairly 

 numerous, small but prominent true oscula formed each by the coalescence of several 

 tubes in a projection from the general surface. The ascon-tubes are only about 

 - 16 millim. in diameter and there is no pseudoderm. The entire colony attains a 

 diameter of some 10 millims, or 20 milbms. The colour in alcohol is pale grey. 



