110 CEYLON PEARL OYSTER REPORT. 



This species is closely related to CARTER'S " StettcttinoptM simplex," from Australia 

 (Fremantle and Port Phillip Heads),* for which SOLLAS (15) established the genus 

 Asteropus, and which, with the doubtful exception of SCHMIDT'S Stellettinopsis 

 annulata, has, up to the present time, remained the only described species of the 

 genus. (TOPSENT has shown (28) that LENDENFELD'S Asteropus incrustans is not 

 referable to the genus Asteropus at all.) 



The occurrence of another species in Ceylon waters is extremely interesting and 

 affords a good illustration of the close relationship which exists between the Sponge- 

 Fauna of this region and that of Australia. That the two species are not identical 

 I have been able to convince myself by personal examination of a fragment of an 

 Australian specimen kindly forwarded to me some years ago by the authorities of the 

 British Museum (Natural History). The differences concern chiefly the arrangement 

 of the vents, the colour (tawny-brown in the Australian species), and the size of the 

 oxea (which are considerably more robust in the Ceylon species). Still, it is possible 

 that the future discovery of intermediate forms may justify us in uniting the two. 



I have taken the liberty of naming this species in honour of the most distinguished 

 author of ' Die Kalkschwiimme.' 



RN. 219 (deep water outside pearl banks, Gulf of Manaar). 



Cryptetethya, n. gen. 



Epipolasidse in which the ectosome is differentiated into a thin, inner fibrous layer, 

 very dense, and a thick, outer, more or less gelatinous layer. The outer layer is 

 produced into more or less elongated, finger-like projections, between the bases 

 of which the more or less spherical body of the sponge is largely concealed by 

 agglutinated foreign bodies. The main skeleton is radially arranged, consisting 

 of large oxea extending through choanosome and ectosome alike. The microscleres 

 are euasters. 



As regards its spiculation, this genus agrees very closely with Coppalias, and, like 

 the latter, is evidently very nearly related to SteHctta. In the structure of the 

 ectosome it makes a close approach to Stelletta herdmani, in which also the trisenes 

 have undergone considerable reduction. In fact, Cryptotethya may be regarded as 

 derived from some such form as Stelletta herdmani by further reduction of the trirenes 

 and by the outgrowth of the ectosome into finger-like processes. In the spherical 

 form of the body, and the radial arrangement of the skeleton, it is also related to 

 Tethya, but perhaps its nearest ally is SOLLAS'S genus Magog, established (15) for 

 the reception of CARTER'S Cliondrilla sacciformis, from Mauritius, and included by 

 SOLLAS amongst the Tethyidse. In Cryptotetliya, however, the oxea are not confined 

 to the choanosome as in Magog. Both genera appear to me to come most naturally 

 amongst the Epipolasida?, though they certainly seem to indicate the manner in 



* Mi-. CARTER (27) also records the species from Hayti, but the Haytian form is very likely specifically 

 distinct from the Australian. 



