102 CEYLON PEARL OYSTER REPORT. 



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

 hut 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, <\/) ; slightly curved and a good deal broader at 

 one end than at the other. The broad end. which may he sliffhtlv tvlote, is covered 

 with minute spines, while the narrow end is smooth, or nearly so. though often with 

 a very few minute projections. Size, commonly about 0*328 millim. by 0'00'J millim. 

 (in the middle). 



So far as 1 am aware, the only other species of Acicvlites hitherto described is the 

 type of the genus, Aciculites higginsii, Schmidt (44), from Havanna. ' >ur 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 ( leylon 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 Tui'sent's Aciculites incrustans has now been recognised by 

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



R.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 

 niicroscleres in the form of sigmata only. 



We have here another proof of the artificial character of Sollas's classification of 

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

 genus Taprobane 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 Aciculites, that Sollas places 

 CScleritbderma 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 tin.' wl<l Greek name tor the Island of Ceylon. 



