ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 351 



New Fresh-water Sponges.* — Mr. E. Potts describes three 

 more curious fresh-water sponges. One {Meyenia crateriforma) is 

 of a very delicate structure ; its framework of skeleton spicules is 

 exceedingly meagre, and slightly bound together, scarcely amounting 

 to a mesh system, and the numerous small white statospheres are 

 found in recesses far larger than themselves. Another {Heteromeyenia 

 ryderii) forms beautiful green masses, often four to five inches in 

 diameter, and about a quarter of an inch in thickness. The surface 

 is irregular, occasionally rising into rounded lobes ; the efferent 

 canals are deeply channelled in the upper surface of the sponge, five 

 or six sometimes con verging to a common orifice. The statospheres 

 are numerous and rather small. There are two series of birotulate 

 spicules. The third species belongs to the genus Tuhella. This 

 genus, established by Carter, contained only four species, all from the 

 Amazon river. The new species is small, encrusting, and has been 

 named T. pennsylvanica. The skeleton spicules are arranged in a 

 simple series of single non-fasciculated spicules, in the interspaces of 

 which the statospheres are abundant. These spicules are very vari- 

 able in size and shape, but all are entirely and coarsely spined. The 

 dermal spicules seem absent. 



Protozoa. 



Organization of the Cilio-flagellata.f — E. S. Bergh gives an 

 account of the Cilio-flagellata observed in the Little Belt and in the 

 fresh waters of Denmark ; the first part containing " History " and 

 " Bibliography," the second a description of ten genera and twenty 

 species, and the third Phylogeny. The chemical composition of the 

 various parts of the body is fully dealt with so far as that is possible 

 by the use of reagents, as well as the anatomical structure. Seventy- 

 three figures show what great variation is presented by certain forms, 

 and how difficult it often is to define the limits of the species. 



The body of all Cilio-flagellata is bilaterally asymmetrical, 

 differing remarkably, however, in the various representatives ; some- 

 times it is compressed from front to back (Dijylopsalis lenticula, 

 Glenodinium Warimngii), sometimes from above downwards (^Ceratium, 

 Peridinium), and sometimes laterally {Binophysis, Amphidinium, Pro- 

 rocentrum). It may be drawn out into horns (Ceratium, Peridinium 

 divergens) or may be destitute of any. 



They possess either a lorica (cell-membrane) (Ceratium, Proto- 

 ceratium, Peridinium, Protoperidinium, Dinophysis, Piplopsalis, Gleno- 

 dinium, Prorocentrum), or are naked {Gymnodinium, Polyhrikos). The 

 membrane consists either of celhilose or a similar hydro-carbon, and is 

 coloured by chlor-iodide of zinc, pale violet [Ceratium, Perid. tabu- 

 latum) or intense red {Perid. divergens, Protoperidinium, Diplopsalis), or 

 even pale red {Prorocentrum, Glenodinium cindum). Those forms 

 which have been closely examined do not contain silica. The more 

 minute structure of the cell-membrane varies much ; it is either 

 transparent and structureless (Glenodinium) or ornamented with 



* Proc. Acad. Nat. Sci. Phila., 1882, p. 12. 



t Morph. Jahrbuch, yii. (1881) pp. 177-288 (5 pis. and 1 fig.). 



