332 Miscellaneous. 



with the others, which had induced him to place it in the genus 

 Ueteromn/enia. For this reason he believed the species were not 

 identical, and this argument fails. 



In continuation he reasoned that it should not be considered a 

 matter of surprise that the statospheres of some genera pertaining 

 to the family of freshwater si:)onges should j^resent tentative 

 features of this character. In a paper published so long ago as 

 1859, Mr. Carter called attention to the resemblance in appearance 

 and function between the statoblasts of the Polyzoa and the so-called 

 "seed-bodies" of SpoiigiUa. The parallelism is rendered more 

 complete when Ave observe that in those forms of Polyzoa possessing 

 a comparativ ly rigid ectocyst, the statoblosts are circular or len- 

 ticular with smooth margins. Some of these are no doubt washed 

 out from the tnbular body fr(^m time to time during the winter, to 

 extend the species to other places ; while enough are retained by it 

 to renew the growth in the original locahty. On the other hand, 

 where the body-mass is simply gelatinous, as in Pectinatdla, Crista- 

 tella, &c., decaying av/ay and releasing the statoblasts on the first 

 approach of winter, these are provided with either a single row or a 

 more complicated series of marginal tentacular hooks, by which they 

 become matted together, entangled with roots, stems, &c., or held to 

 rough places on planks or stones. 



The same relation to the permanency of their skeleton structure 

 we find existing amongst these genera and s})ecies of freshwater 

 s])onges. The statospheres of nearly all species are provided with 

 some anangeraent for protection and retention. These vary greatly 

 in kind and degree, inversely according to the protection afi^brded 

 them by tlie surrounding skeleton. Perhaps the lowest in the 

 series in this regard is Mcj/enia Lci<Ii/i. This is a thin incrusting 

 sponge, the skeleton-spicula stout and firmly matted together, 

 maintaining the position of the form and the mass throughout the 

 year. The statospheres are formed in the autumn, in the lowest 

 parts of the sponge, within special capsules formed by interlacing 

 spicula. It is hardly possible these should wash away ; and 

 accordingly we find no means provided peculiar to themselves for 

 detaining them. Their ai-mour consists of a closely laid series of 

 birotulate spicula with entire margins, excellent as a shield, but 

 hopelessly useless as a means of retention. On the other hand no 

 apparent means of diffusion are provided; and as a consequence the 

 species seems to be extremely local, none having been noticed 

 except in the stream where the first specimen was gathei'cd, and 

 within a few yards of the probable spot. 



Sponr/ilhi frarjilis of Leidy, when seen during the summer-time, 

 nearly resembles in form the above-mentioned s^Dccies ; its skeleton- 

 structure, however, is miv:;li more fragile, and is fre(]uently detached 

 and washed away, leaving a uniform series of statoblasts standing- 

 side by side, with no special coating of spicules for each, as in most 

 other species, but grouped and held together by a common coating 

 of cellular or granular matter, covered by and imbedding a great 

 number of cylindrical spined sjjicules. A variety of this is often 

 observed (whether it differs specifically in other respects he could 



