236 ARTHUR DENDY. 



(8) and Vosmaer (14) in a very different sense, I have thought 

 it desirable to make use of the name chosen. 



I believe that very probably the genus will still require sub- 

 dividing at some future date, but it will be an extremely 

 difficult matter to satisfactorily characterise the different sub- 

 divisions ; the irregular nature of the skeleton appears to 

 me to defy classification. It might be possible to maintain 

 Gray^s genus Aphroceras for species like Leucandra 

 alcicornis, in which the dermal cortex is composed chiefly of 

 longitudinally arranged oxea. Aphroceras would then stand 

 in the same relation to Leucandra as Ute does to Grantia; 

 but, unfortunately, we find species intermediate in skeletal 

 characters between the typical Leucandra and the proposed 

 Aphroceras, in which we have large oxea in the dermal 

 cortex, but not arranged with regularity parallel to the long 

 axis of the sponge, nor yet projecting at right angles from the 

 surface. I have already expressed my hesitation in maintain- 

 ing the genus Ute; and as the genus Aphroceras has not, 

 like Ute, come into general use, I do not care to take upon 

 myself the responsibility of re-establishing it. 



Certain species of Leucandra, as already pointed out in 

 dealing with the skeleton, still exhibit traces of descent from 

 a radially symmetrical form, in the presence of subgastral and 

 other sagittal triradiates ; and for the present we may con- 

 veniently regard the genus as being descended from an ancestral 

 Grantia type, by modifi.catiou of the canal system and skeleton 

 along the lines laid down in an earlier part of this paper. 



The true relations of many species of the genus are obscured 

 by the habit of colony formation by the fusion of many 

 individuals, which gives rise to irregular, massive sponges, as 

 in the case of Synute ; but I do not think that we can 

 generically separate these species from those which retain the 

 more primitive condition, with a single central gastral cavity. 

 My Leucandra phillipensis (4), the anatomy of which 

 is drawn in fig. 16, is a typical example of the simpler section 

 of the genus, while the European Leucandra nivea (5) offers 

 an illustration of the massive colonial habit. Numerous other 



