276 J. G. WALLER ON THE BURROWING SPONGE. 



theory. It is, however, drawn from a dried, and not a living speci- 

 men. 



Dr. Bowerbank does not describe nor seem to have seen the ova 

 nor any organs of reproduction of this sponge. He, however, quotes 

 Dr. Grant, who states that " during the months of March and 

 April, when his observations were made, numerous small yellow 

 ova were seen in the vicinity of the canals, agreeing much in their 

 form, size, and mode of distribution with those of Spongia papil- 

 laris and S. panicea." It was at the end of the month of March 

 that I procured the oyster which has afforded me so much informa- 

 tion on this subject. And, in secluded nooks of the excavations, 

 generally nearest to the older and more mature portions of the 

 sponge, I found numerous ovaria, using the distinction Dr. Bower- 

 bank makes between them and the gemmule, embedded in the sar- 

 code and protected by a somewhat rudely-formed network of fas- 

 ciculi of spicula. They were oval in shape, and measured about 133rd 

 of an inch in their long diameter. (Fig. 4.) When mounted in 

 Canada balsam these were found to consist of numerous vesicles or 

 ova, not dissimilar from those found in the fresh-water sponges. 

 In their natural state they are of a bright yellow colour, -and semi- 

 transparent, but when about to leave their investment become denser, 

 paler, and mOre opaque. To view their general appearance and 

 arrangement they are better mounted dry, but the vesicles cannot 

 be seen until mounted in balsam. Besides these organs there are 

 others much more minute, being simple, ovate cells, and these are 

 not collected together in particular spots, but are found scattered 

 over the membranes, sometimes in such quantities as to resemble 

 the spores of a fern, and often giving a deep chocolate hue to the 

 membranes. They are generally much more numerous near the 

 mouths of the oscula, where they seem to be in the act of escaping 

 from the parent. They measure 2150 of an inch in the long dia- 

 meter. (Fig. 5.) 



What relation these may have to "the other I cannot pre- 

 sume to say ; it is a point for other observers to take up.* And 

 it is important to let the time for study be the months of March 

 and April, when they are developing into maturity. Not but what 

 it is necessary to observe such organisms as sponges at all times of 



* Possibly these may be spermatozoa. 



