134 PROGRESS OF MICROSCOPICAL SCIENCE. 



the two classes. He gives the following account of an intermediate 

 form. He says that in Schultze's ' Archiv. fiir Mikroskopische Ana- 

 tomic,' * Cienkowsky describes, imder the name Phalansterium, a genus 

 which consists of monad-like bodies with a flagellum and a projecting 

 collar like those of Codosiga, Saljnngoeca and Leucosolenia. Of the two 

 species which he illustrates, one (P. consociatum) has monads enveloped 

 in a broad funnel-shaped, slimy sheath, and these sheaths are closely 

 packed side by side, radiatingly, so as to form a shield-like or a hemi- 

 spherical mass. This comes nearest to the Salpingoeca. The other 

 species (P. intestinuini) possesses similar monads, but they are im- 

 bedded basally in a gelatinous, intestiniform mass of slime (Schleim), 

 " with their vibrating lashes extending in every direction " about the 

 cylindrical colony. Originally each monad is endowed with a sepa- 

 rate slime-sheath ; but eventually these all are fused together into one 

 common mass. Beyond this, to make a true Sponge we need but the 

 presence of spiculas, and open interspaces in the slimy mass, between 

 the monads, leading to one common cavity. Introvert the layer of 

 monads, and we produce the desii'ed effect without doing violence to 

 their relative positions. It is a mere matter of proportions, just as the 

 inverted cyathiform rose-hip is none the less an ovariferous disk than 

 the globular receptacle of the strawberry. 



Striated Muscular Fibre in Gasteropoda. — Mr. W. H. Dall (of 

 America) says that in studying the radula of a species of Acmcea 

 (probably A. Borneensis, Eve), obtained by Professor A. S. Bickmore 

 at Amboyna, he noticed, on placing the structure under a power of 

 100 diameters, that certain of the muscular fibres which adhered to it 

 when torn from the buccal mass, had a different appearance from the 

 others. On increasing the power to some 800 diameters, it was at 

 once evident that the different aspect of these fasciculi was caused by 

 fine, but clearly defined, transverse striation. Suspecting that it was 

 an optical delusion, caused by a very regular arrangement of the 

 nuclei of the fibres, he subjected the muscle to various tests and to 

 still higher magnifying powers. He also introduced under the same 

 glass, some of the voluntary dorsal miiscles of a small crustacean, for 

 comparison. The structure of the ultimate fibres in both appeared to 

 be similar. These seemed to be composed of a homogeneous tube or 

 cylindrical band of translucent matter, with nuclei intersi)ersed at 

 irregular intervals. In neither was there any appearance of separa- 

 tion into transverse disks, as is seen in the striated muscles of verte- 

 brates. That the striated appearance was not due to contraction and 

 folding of the muscle was evident ujion taking a side view of one of 

 the fibres, when the strise on each side, as well as the intervening 

 elevations, were seen to correspond exactly to each other. The only 

 perceptible differences between the muscles of the crustacean and the 

 striated muscles of the mollusk, appeared to be that the latter were 

 much more finely striated ; the striae being six to eight times as nume- 

 rous as in the former, in the same sj)ace. No difference between the 

 striated and non-striated muscles of the Acmcea could be observed, 



* Bd. vi., 4, 1870. 



