212 



THE AMERICAN MONTHLY 



[November, 



globular, and more or less tubercu- 

 latecl. Crust very thick, composed of 

 micro-cellular structure, which grows 

 out through the intersticies of the re- 

 ticulated arrangement of the skeleton 

 spicules, and forms somewhat of a 

 capsular covering to the statoblast, as 

 in TuhcUa, giving it the tuberculated 

 appearance just mentioned. It is 

 charged with, and surrounded by, 

 minute, thin, curved, fusiform, gradu- 

 ally sharp-pointed, spinous, acerate 

 spicules, irregularly dispersed through 

 the substance, limited, both inside and 

 outside, by a layer of parmuliform spic- 

 ules, the former in contact with the 

 chitinous coat, and the latter on the 

 free surface of the crust, giving it a 

 light-brown color. The parmuliform 

 spicule is circular, flat, infundibuliform, 

 terminating in a point, like a little 

 round shield turned up at the margin, 

 which is even. The spicules are ar- 

 ranged both internally and externally 

 in the statoblast in juxtaposition, more 

 or less overlapping each other, with 

 the funnel-shaped process outwards 

 in both instances, so that the surface 

 is covered with little points. 



The sponges comprising Tiibdla 

 and Parmula possess an extremely 

 rigid reticulated structure, as also the 

 next and last genus, Uriiguaya, so 

 named from having been found in the 

 rapids of the river Uruguay. The 

 only species is U. corallioides of which 

 the statoblast has not yet been dis- 

 covered. 



Dr. Dybowski has, I believe, found 

 sponges in lake Baikal, in Central 

 Asia, including a new genus, Z?^/;^;«/r- 

 skia, comprising four species with their 

 varities, but the statoblasts were ab- 

 sent in all of them. Without taking 

 these into consideration, we have 

 thus five genera of fresh-water sponges, 

 including 24 species, in only one of 

 which the statoblast is unknown. Two 

 oniv of these have been found in the 

 British Isles, varying in structure ac- 

 cording lo locality, etc. It would not 

 surprise me if other species should be 

 found some day, particularly as they 

 seem to have existed in former years 



in larger numbers of species, as proved 

 by the presence of the amphidiscs and 

 spicules found in fresh-water deposits, 

 many of which are different in form 

 from those at present known. 



Referring to what I stated at the 

 commencement of this paper, that 

 statoblasts do not occur in any known 

 marine sponges, I have been asked 

 occasionally, " What then do you call 

 the bodies found in Gcodia and Pachy- 

 matisfiia, and termed by the late 

 Dr. Bowerbank.ovaria ?" My answer 

 is that they are certainly not ovaria. 

 Dr. Bowerbank was evidently mis- 

 led by the depressions which are 

 found to exist in these bodies. If we 

 break up any of them, as I have often 

 done, from their earliest form of 

 development we shall find that it is 

 merely a depression and not an aper- 

 ture leading to an internal cavity, as 

 no such cavity exists, and that the 

 "globular crystalloids," as they are 

 now termed, are consolidated aggrega- 

 tions of spicules radiating from the 

 centre to the circumference, and form- 

 ing one solid mass, being no more 

 ovarian than the stellate forms of 

 spicules found in Tct/iya, or the 

 silicious or calcareous bodies found 

 packed in the cells of some of the 

 tunicated ascidians. Dr. Bower- 

 bank's statement of their being ovaria, 

 moreover, is not borne out by the 

 figures intended to illustrate what he 

 says. For further particulars, a paper 

 by Mr. Carter in the Annals of 

 Natural History for July, 1869, con- 

 taining remarks on the same subject, 

 may be consulted. 



Since writing this, Mr. Carter has 

 kindly sent me a copy of his paper in 

 the Annals of Natural History for the 

 present month, describing a new 

 species from Bombay, Spongilla Bom- 

 baycnsis ; and also calling attention to 

 one shortly to be published and 

 described by Mr. Potts of Philadel- 

 phia, found at Chester Creek, Spongilla 

 st'gregata, the statoblasts of which are 

 developed in a capsule, four together ; 

 the capsule being composed of hexa- 

 gonal cells, such as are found in S. 



