1887.] NATURAL SCIENCES OF PHILADELPHIA. 259 



increased with the growth of the sponge, until, near their ends, their 

 thickness may be that of 30 to 50 skeleton spicules en fascicle. In 

 its living condition, of course, these lines of spicules were clothed 

 with sarcode, and the outer surface, without doubt, was surrounded 

 by a dermis of greater or less density, giving the sponge more the 

 appearance of a solid mass than it has at present. The dermal spic- 

 ules above described were found in some small patches of adherent 

 brown substance, where they were associated with the proper skele- 

 ton and capsular spicules of this species and are therefore assumed 

 to belong to it though not found in situ. 



The gemmules are here a very interesting feature. Throughout 

 the outer half inch of the mass, they are seen attached to every 

 spicular thread, less like beads than grapes, and ajij^ear to have 

 been formed at the close of the season of growth, or just before the 

 retirement of the waters, left the sponge hanging in mid-air. It is 

 of course important to learn, so far as may be possible from the ex- 

 amination of this specimen, whether the whole of the mass was 

 formed during a single period of submergence. If not, I argue 

 that another zone should be found within the first, formed at the 

 termination of a previous season, the germination and colonial 

 growth of whose gemmules would give rise to the "second story" of 

 this structure. This appears to be the case. A spherical space of, 

 say, one and a half inches diameter, at the centre of the mass, is 

 charged Avith gemmules, while between this and the outer zone of 

 gemmules, a space more than an inch in breadth is almost or entire- 

 ly clear of them. It is supposable, therefore, that this specimen 

 represents a growth of two years, at least of two seasons of sub- 

 mergence, and that the life of the sponge, whether it be in the con- 

 dition of ova or of resting spores merely, has been preserved in the 

 gemmules in despite of, say, eight or ten months of absolute desic- 

 cation.^ 



(3) Parmula rusbyi, n. sp. 



Sponge minute, parasitic upon P. brownil, v. tuberculata ; Spicules 

 non-fasciculate. Mass, as seen, with no definite outline. 



^After writing the above, it occurred to me to attempt the germination of some of 

 the gemmules under consideration, and in one instance, within two days, and in 

 another, in six hours after placing a few in water, an extvusion of germinal 

 mattef was observed. In neither case has this yet resulted in a recognizable 

 embryonic sponge, but they sufficiently evidence continued vitality. 



