468 DR. J. S. BO-WERBANK ON THE SPONGILLID^. [NoV. 24, 



those of the European species. They are usually of the regular 

 acerate form, but occasionally become subfusiform. 



The spicula and their mode of arrangement in the dermis of the 

 OTarium cannot be readily seen without the aid of treatment with hot 

 nitric acid, in which they should be immersed for a few seconds, and 

 the acid should then be immediately diluted with water, after which 

 they should be dried on the glass on which they are to be mounted 

 in Canada balsam. The spicula in the dermis of adult ovaries are 

 very abundant. They are similar in form and proportions to those 

 of the dermal membrane ; but, generally speaking, they are more 

 fully produced, and the greater portion of them are subcylindrical 

 from the profusion of spines at their apices. Their form and mode 

 of arrangement in the ovary render them exceedingly valuable as 

 specific characters. In some of the young and incompletely deve- 

 loped ovaries I could not detect a single specimen of these spicula. 

 The only difference I could find between these spicula and those of 

 the dermal membrane was, that the spines on those of the latter 

 were more sharply and fully produced, while on those of the ovary 

 they were frequently ill-defined and often only in an incipient state, 

 but very abundant. 



In the preparation of the spicula for examination I found a few 

 birotulate ones having the rotulse very deeply divided. These spicula 

 were no part of the Sponge in course of description, but were un- 

 doubtedly from the gemmules of another species inhabiting the St. 

 Lawrence. 



Spongilla cinerea. Carter. 



Sponge sessile, massive; surface even. Oscula numerous, dispersed, 

 large, more or less depressed. Pores conspicuous. Dermal and 

 interstitial membranes spiculous ; spicula fusiformi-acerate, small, 

 entirely spined. Skeleton-spicula fusiformi-acerate, incipiently spi- 

 nous. Ovaries globose ; spicula acerate, slightly curved, entirely 

 spined ; spines conical, acute, at right angles to the shaft ; spicula 

 disposed at right angles to lines radiating from the centre of the 

 gemmule. 



Colour dark purple or rusty copper {Carter'). 



Hab. Freshwater tanks, Bombay. 



Examined in the dried state. 



Mr. Carter says of this Sponge, " While the investing membrane 

 of this species remains intact, its surface presents a dark rusty copper- 

 colour, purplish under water. It never appears to throw up any 

 processes, and extends over surfaces of 2 and 3 feet in circumference, 

 or accumulates on small objects to the thickness mentioned. It is 

 distinguished from the other species by its colour, the fineness of its 

 texture, and the smallness of its seed-like bodies and spicula." 



I have received three specimens of this species from Mr. Carter ; 

 in all of them the oscula are large and considerably depressed, and 

 the spaces between them generally abound with, comparatively, large 

 and very conspicuous pores, which are not depressed like the oscula. 



