PKOGBESS OF MICBOSOOPIOAL SCIENCE. 205 



pairs of maxillij)cds, or all of them, are developed into locomotive 

 organs. In no period of their development do they have all the 

 decapodal legs furnished with natatory exopodal branches. There are 

 undoubtedly larval forms closely allied to those of Homarus in some of 

 the groups of Macrourans, although they appear to be as yet unknown. 

 " Notwithstanding these larval forms of the lobster seem to have 

 no close affinities with the known larvfe of other genera of Macroiu-ans, 

 they do show in many characters a very remarkable and interesting 

 approach to the adult Schizoijoda, particularly to the Mysidte. This 

 appears to me to furnish additional evidence that the Schizopods are 

 only degraded Macrourans much more closely allied to the Sergestidje 

 than to the Squilloidea." 



What is a Sponge ? — This seems a more difficult question than 

 ever it has been. Haeckel has recently confirmed in great measure 

 Mr. Carter's view, that it is a collection of Amoebfe-like infusoria, 

 living among a framework of silicious or limestone s^iicules. A little 

 later than Carter, the lamented Professor H_. J. Clark, of America, 

 published, in 1866, a i)aper in which he maintained that the sponge 

 was an aggregation of flagellate infusoria, like monads of the genera 

 Monas, Anthophysa, Godosiga, &c. The sponge, then, in his view was a 

 compound protozoan animal. Now Haeckel contends that these 

 monads of Clark are simply cells lining the general stomach-cavity of 

 the sponge, each bearing a cilium or thread, and that the sponge is 

 not a compound infusorian, but a much more highly organized animal 

 related to the radiates, such as the Polyps (Hydra, &g.). He dis- 

 tinguishes in them a general cavity or stomach, the walls of which 

 consist, as in the Acalephs, of two layers (entoderm and exoderm) of 

 cells. He regards the sponges and Acalephte as having been evolved 

 from a common ancestor, which he terms Protasciis. 



Quite recently the editor of the ' American Naturalist ' has 

 received a paper by Metschnikoff on the development of a calcareous 

 sponge (Sycon ciliatum). He clearly proves that Haeckel's view of the 

 structure of the sponges was correct, but shows that there is no real 

 relationship between the sijonges and radiates. 



Tolcelau Bingioorm and its Fungus.— Dr. T. Fox has given in the 

 ' Lancet ' (Aug. 29) an interesting paper on the above subject. He 

 says that there is a form of eruption which appears to be very common 

 at Samoa, the hitherto unknown cause of which he has recently been 

 able to discover ; and he seeks this oj)portunity of placing the main 

 facts in regard to it before the profession. The Rev. Dr. Turner, M.D., 

 refers to the disease, in liis First Annual Report of the Samoan 

 Medical Mission, under the term " Tok^lau Ringworm," or " Lafa 

 Tokelau"; so named from its having recently been introduced to 

 Samoa from Tokelau or Bovvditch Island. Dr. Turner says, " It is a 

 scaly disease, much more like ichthyosis in its general aj^pearance 

 than any other disease with which I am acquainted. The scales, how- 

 ever, differ from those of ichthyosis, in that they are not disposed in 

 squares. They run in concentric circles, and may be w-ell represented 

 by taking a sheet of stout cardboard and shaving the upper layer of it 



