254 CEYLON PEARL OYSTER REPORT. 



the summits of the hranches have a yellowish tinge. When living, the zooids were 

 of a pale hrown colour, which, however, has been dissolved by the spirit preservative. 



A specimen from Aripu is smaller. It is 50 millims. high and measures 45 millims. 

 by 35 millims. across the surface of the capitulum, which is seamed at the margin. 

 In spirit the stalk is light brown and the capitulum yellowish-drab. When living, 

 the capitulum was a pale yellowish-green colour. 



The fragmentary specimens are of a uniform drab colour. All the specimens arc 

 moderately hard, yield slightly to the touch, and are somewhat brittle. 



The species is monomorphic. The autozooids appear to be rudimentary. They are 

 extremely small, numerous, and are arranged with great regularity on the capitular 

 surface. The average surface diameter of a contracted autozooid is 0'04 millim. 

 Frequently as many as 20 zooids may be counted in a linear centimetre. Tt is 

 unfortunate that the preservation of the specimens will not permit of a more complete 

 investigation of the anatomy of this interesting species. 



The ventral mesenterial filaments are extremely small, but the dorsal filaments are 

 as well developed as in other species. The superficial and internal canal systems do 

 not differ in any essential respect from those of other species. The endodermal tissues 

 and canals are crowded with zoochlorellse. The minuteness of the ventral mesenterial 

 filaments and the smallness of the autozooids is doubtless correlated with the extreme 

 abundance of zoochlorellaa, and is discussed in a paper now in the press (PiiATT, 

 1905). 



The Spicules (fig. 9) are similar in character to those of other species. Tuberculate 

 spicules usually in the form of spindles, but sometimes forked, are comparatively 

 numerous, and average 3 millims. in length and 0'5 millim. in breadth. Clubs some- 

 times with spiny handles, and spindles set with minute spines, are closely packed near 

 the surface, so as to form an outer crust. The average size of the clubs is 0'09 millim. 

 by 0'04 millim., of the spindles 0'25 millim. by 0'03 millim. A few spiny crosses 

 also occur. 



Sclerophytum marenzelleri, WRIGHT and STUDER (1889). 



A single specimen of this species was taken in the Gulf of Manaar. 



The colony forms an extremely hard cake-like mass, with lobes of varying size 

 arising vertically from the upper surface of the capitulum. The basal attachment 

 consists of hard coral encrusted with Polyzoa and shells. The colony is 93 millims. 

 high ; the capitulum has a transverse diameter of 337 millims. by 257 millims ; the 

 stalk is 55 millims. in height and is irregular in outline. The capitulum has a well- 

 marked marginal seam and bears numerous conical lobes many being fully 20 millims. 

 high. A few of the lobes are branched. 



The specimen in spirit is of a pale pinkish-brown colour, which originally was 

 doubtless of a more intense hue, as the spirit is of a golden-brown colour. The 

 capitulum is tough in consistency and slightly yielding to pressure ; that of the stalk 



