102 CEYLON PEARL OYSTER REPORT. 



end in rather sharp, conical papillae. Similar papillae may occur on the main axis, 

 but when this is strongly curved they are usually absent from the concave side. The 

 fully developed desma measures about 0'328 millim. in maximum length in a straight 

 line from point to point. 



(2.) Strongyla (Plate IV., fig. 3, e,f) ; slightly curved and a good deal broader at 

 one end than at the other. The broad end, which may be slightly tylote, is covered 

 with minute spines, while the narrow end is smooth, or nearly so, tin nigh often with 

 a very few minute projections. Size, commonly about 0'328 millim. by - 009 millim. 

 (in the middle). 



So far as I am aware, the only other species of Aciculites hitherto described is the 

 type of the genus, Aciculites higginsii, SCHMIDT (44), from Havanna. Our species is 

 evidently very closely related to the West Indian form, which has fortunately been 

 re-examined and described by SOLLAS (15, p. 347). In fact, the only specific 

 difference which the description of the latter has enabled me to detect lies in the fact 

 that in the Ceylon species the vents are not protected by tent -like arrangements of 

 radiating rhabdi as described by SOLLAS. Probably, however, other specific differences 

 will be found to exist in the form of the desmas, &c. 



We have here an interesting case of apparently discontinuous generic distribution, 

 though the imperfect state of our knowledge of the sponge-fauna of intermediate 

 localities makes it possible that the discontinuity is apparent rather than real. 



It may be noted that TOPSENT'S Aciculites incrustana has now been recognised by 

 that author as belonging to a totally distinct genus, Desmanthus (14). 



E.N. 150 (Ceylon seas). 



Taprobane,* n. gen. 



Lithistida of plate-like or cup-shaped form, with minute sphinctrate apertures 



abundantly scattered on each side of the plate ; with monocrepid, tuberculate 



desmas and long, slender oxea ; without special ectosomal spicules and with 

 microscleres in the form of sigmata only. 



We have here another proof of the artificial character of SOLLAS'S classification of 

 the Lithistida. It will be seen from the diagnosis that the sponge upon which the 

 genus Taprobanc is based might be regarded either as a Scleritodermid without 

 ectosomal spicules or as an Azoricid with sigmata ; it is thus very closely related on 

 the one hand to Scleritoderma, and on the other to Azorica. We have already had 

 occasion to notice, in speaking of the genus Aciculitt's, that SOLLAS places 

 iScleritoderma and Azorica in different " sub-orders," his Hoplophora and Anoplia 

 respectively, but the discovery of Taprobane, combining characters of these two 

 groups, viz., the absence of special ectosomal spicules and the presence of microscleres, 

 alone seems sufficient to necessitate a revision of SOLLAS'S scheme. 



* So called from the old Greek numu lor the Island of Ceylon. 



