152 CEYLON PEARL OYSTER REPORT. 



the spicules; owing to its very pale colour and great transparency, however, it 

 readily escapes observation. Numerous spicules occur scattered irregularly between 

 the fibres. There is no special dermal skeleton, the dermal membrane being practically 

 destitute of spicules. 



Spicules. Slender, slightly or rather strongly curved oxea ; more or less gradually 

 sharp-pointed at the ends; size variable, say about 0'12 millim. by 0'003 millim. 



It is probable that this species is identical with ESPER'S Spongia cymoeformis (from 

 Ceylon). It also appears to be nearly related to Chalina palmata from European. 

 Indian and Australian waters ; differing, however, in the absence of the dermal 

 skeleton reticulation. In habit the species reminds one very much of some species of 

 A.iinella, a resemblance which appears from EHLEBS' description to have been 

 increased in the case of ESPER'S specimen by the presence of styli mingled with 

 the oxea. 



RN. 16 (Gulf of Manaar) ; 349 (Stat. LV., west of Periya Paar, 20 fathoms). 



Ceraochalina, LENDENFELD. 



Chaliuiuae of varioiis external form ; not tubular. Texture hard, owing to the great 

 thickness of the skeleton fibres, in which the spongin is very strongly developed 

 and the spicules much reduced in size and sometimes also in number. 



Ceraochalina retiarmata, n. sp. Plate X., fig. 4. 



The single specimen forms an erect, thin lamella, attached below by a constricted 

 base ; sub-dividing into flattened branches and giving off irregular digitiform 

 processes almost exclusively in one plane ; the branches to a slight extent anastomosing 

 with one another. Surface glabrous, minutely granular under a lens ; rather uneven. 

 Vents minute, about 0'5 millim. in diameter, mostly arranged uniserially on the 

 narrow margins. Inhalant pores scattered in the meshes of the dermal reticulation. 

 Colour (in spirit) rather dark brown ; texture compressible, resilient, tough and 

 fibrous. Total height of specimen about 33 millims. ; greatest breadth about 

 66 millims. ; thickness of lamella about 3 '5 millims. 



The main skeleton is a network of stout horny fibre, sparingly cored by very 

 slender vestigial oxea. The primary fibres are about O'l millim. in diameter and 

 curve upwards and outwards towards the surface, branching as they go. They are 

 connected together by short secondaries about 0'05 millim. in diameter and containing 

 fewer spicules. There is also a system of tertiary fibres, much more slender (from 

 about U'008 millim. to about 0'024 millim. in diameter) and containing from one to 

 about four rows of well-developed oxea imbedded in spongin. These tertiary fibres 

 form an irregular network which seems to bear no relation to the rest of the mam 

 skeleton, except that its fibres are attached frequently to those of the latter. 



The dermal skeleton is very strongly developed, forming a close polygonal-meshed 

 reticulation of horny fibres cored by usually two or three rows of well developed oxea 



