TRWHOPLAX, THE JJICYEMID^! AND ORTHONEVTW^E. 63 



CHAPTER IV. 



IRICHOPLAX, THE DICYEMID^E AND ORTHONECTID^E. 



BEFORE passing on to a description of the first type of 

 Metazoa, it will be necessary to consider a few forms wliich 

 can hardly be assigned to it and yet present too great a dif- 

 ferentiation of their component cells to warrant their reference 

 to the Protozoa. A third subkiugdoro, the Mesozoa, has been 

 proposed for them, but until more is known of the relations 

 of some of them at least to other forms the establishment of 

 such a subkingdom seems inadvisable. 



Triclioplax adhcerens. 



FIG. 30. A, SURFACE VIEW AND B TRANSVERSE SECTION THROUGH Tricho- 



plax (after SCHULZE). 

 b = botryoidal slructure. r = refractive bodies. 



In the marine aquaria at Gratz, Vienna, and Berlin there 

 has been found a small organism (Fig. 30, A) measuring from 



