1^.2 Records of the Indian Museum. [Vol. X, 



There is one anatomical feature of the Spongillidae which I 

 have left to the last in considering the distinctive features of the 

 family, because I am not sure of its precise significance; I mean 

 the well-developed subdernial cavities Under this term two quite 

 distinct structures or rather systems have sometimes been confused, 

 viz. {a) the cavity between the derma and the parenchyma in ^o 

 which water is drawn through the dermal pores on its way into 

 the inhalent or afferent channels of the sponge, and (b) the 

 superficial exhalent or efferent channels that extend along the 

 surface of the parenchyma immediately beneath the derma and 

 open into the oscula direct. Both these systems may be traced in 

 all Spongillinae and in Nudospongilla among the Potamolepidinae, 

 although the actual dimensions of the channels differ in different 

 species. In Corlispongilla and Pachydictyitm they can also be 

 detected, but not so easily. I have examined only dry specimens 

 of Potamolepis, but the structure of the skeleton certainly suggests 

 their presence in this genus also. 



In the Haploscleridae (as also in man}- other marine Monaxon 

 sponges) many genera and species have both systems well develop- 

 ed. This is the case in many of the Renierinae, the subfamily 

 most nearly related to the Spongillidae. It is not the case, 

 however, in the Chalininae. In this subfamily (or at any rate in 

 all its representatives I have examined) there is practically no 

 subdermal inhalent cavity and the main exhalent channels run up 

 vertical or obliquely to the surface of the sponge, on which they 

 open as a rule in groups. 



In all the Baikal sponges I have examined, or of which 

 suitable figures have been published — I have not seen the forms 

 of Spongilla and Ephydatia described by Swartschevski (1901), 

 whose figures do not illustrate this point — both subdermal systems 

 appear to be absent and the structure of the sponge is in this 

 respect exactly like that of the Chalininae, the distal part of 

 the vertical or radial fibres of the skeleton being buried in the 

 parenchyma to their tips, instead of standing out above the 

 parenchyma and supporting the dermal membrane as a tent-pole 

 supports a tent. Stress has been laid by Dybowski and others on 

 the "grouped" nature of the oscula in the Baikal sponges, and 

 this would seem to be a character usually correlated with the 

 absence of an exhalent subdermal sytem. In the Potamolepidine 

 sponge Nudospongilla aster from Palestine, however, it is not so. 



Family HAPLOSCLERIDAE. 



Subfamily CHALININKZ. 



Genus Lubomirskia, Dybowski. 



This genus may be defined as follows : — 



Sponge massive, consisting of upright cylindrical stems or 

 flabelliform, tough, elastic, not at all friable, with shallow oscula 

 scattered, as a rule in groups, on the surface ; main exhalent 



