STUDIES ON THE COMPARATIVE ANATOMY OF SPONGES. 245 



impossible it is to draw a sharp line of distinction between 

 the two types. 



The genus Leucilla was founded by Haeckel (5) for Leu- 

 conoid sponges in which the spicules are all quadriradiate, of 

 course without regard to the arrangement of the skeleton. 

 The first species which he describes is Leucilla amphora^ 

 and I have taken this as the type of the genus^ and constructed 

 the generic diagnosis accordingly. The only other species 

 described by him^ L. capsula, also comes into the genus as 

 now constituted. It thus appears that our Leucilla is a 

 much more comprehensive genus than Haeckel'sj and this is 

 because we include in the genus species with triradiate and 

 oxeote spicules. 



PolejaeflF(8) has attached a very diflPerent significance to the 

 name Leucilla, giving to the genus much the same character 

 as von Lendenfeld has given to his family Sylleibidse ; indeed, 

 the latter was founded (11) chiefly upon Polejaeff''s Leucilla. 

 I revert, however, to Haeckel's two species, and make their 

 characters the foundation of the genus. 



In my synopsis of the Australian Calcarea Heterocoela 

 (4) I, somewhat unnecessarily I fear, proposed the name 

 Paraleucilla for Haeckel's Leucandra cucumis, which is 

 characterised by the presence of distinct subdermal cavities 

 supported by a somewhat specialised portion of the skeleton of 

 the chamber layer. I now regret having taken this step, the 

 more so as PolejaeflF (8) had previously proposed the name 

 Pericharax for the same sponge. Polejaeff, however, also 

 included in the genus Pericharax his P. Carteri, which is a 

 very difi^erent sponge from Leucandra cucumis, and does not 

 even come within the limits of our family Amphoriscidse. 

 I do not now think that either Pericharax or Paraleucilla 

 ought to stand as a distinct genus. Polejaefi''s Pericharax 

 Carteri is but a slight modification of the ordinary Leu- 

 candra type, while HaeckeFs Leucandra cucumis is a 

 similar modification, only rather more marked, of the Leucilla 

 type. 



