232 ARTHUR DENDY. 



ranged radially around the central gastral cavity ; they are not 

 provided with tufts of oxea at their distal ends, but are covered 

 over by a dermal cortex composed principally of triradiate 

 spicules, and without longitudinally disposed oxea. An ar- 

 ticulate tubar skeleton is present. 



Remarks. — The genus Grantia, as here defined, is very 

 nearly co-extensive with the same genus as employed by 

 Polejaeff" (8). It appears to me, however, that the genus must 

 be limited to those species in which no tufts of oxea are 

 developed on the ends of the radial chambers, in order to define 

 it with desirable sharpness from Sycon; for, as I have already 

 shown, we meet with the first indications of a dermal cortex 

 in the latter genus. Hence I cannot agree with Polejaeff 

 in including Sycon (Grantia) compressum. Nor can I 

 agree with von Lendenfeld's diagnosis (10), for he expressly 

 states that a crown of radial " Thabden " may be present on 

 each chamber, and his diagnosis is so worded as to exclude 

 Haeckel's G. (Sycetta) strobilus and G. (Sycetta) cupula, 

 which, as was recognised by Polejaeff (8), undoubtedly belong 

 to the genus Grantia. 



Sub-genus Grantiopsis, Dendy (4), fig. 11. 



Diagnosis. — The sponge has the form of a greatly elon- 

 gated hollow tube, whose wall is composed of two distinct 

 layers of about equal thickness. The outer (cortical) layer 

 is provided with a very strongly developed skeleton of radiate 

 spicules, and is penetrated by narrow, ramifying, inhalant 

 canals. The inner layer is formed by elongated radial 

 chambers, arranged very regularly side by side. The skeleton 

 of the inner layer is very feebly developed. The tubar 

 skeleton is articulate, and composed of very abnormal sagittal 

 triradiates whose paired rays are greatly reduced. 



Remarks. — This genus is obviously only a very special 

 modification of the well-known Grantia type, although at 

 first sight, especially as regards external form, it appears 

 very distinct. The only species known is the Victorian 

 Grantiopsis cylindrica (4). 



