THE RHIZOPODS. 



593 



Order II., SILICOIDEA, includes the highest of the class. The skeleton framework of these 

 Sponges is almost wholly made up of silicious spicules. The TetJiia and Geodia are promi- 

 nent forms. 



What are known as Glass Sponges are of this Order. 



The ffyalonema, or Glass-rope Sponge, is found in the waters around the Philippine 

 Islands. Though so much in appearance like spun glass, it is nevertheless of horn, like the 

 nails and hoofs of animals. When burnt it has the same odor as horn. In 1860 naturalists 

 first found the true nature of these objects ; they, 

 as well as the glass vases, were so artificial in 

 appearance that they were taken as objects made 

 up for a market. 



The Holtenia carpenteria, seen in the engrav- 

 ing, is another of different shape. Of all, for beauty 

 and singularity, the Euplectella, or Glass Vase 

 Venus-cup is the most beautiful A very fine 

 example is here figured. This, it will be remem- 

 bered, is the framework of a Sponge, just as the 

 Sponges we use are frameworks of the Sponge. 

 While alive all Sponges are quite heavy, some ex- 

 ceedingly so, with their flesh and the inclosed 

 water. When lifted from the sea, an old black hat 

 with many holes, is as good an illustration of the 

 looks of a living Sponge as any. But what beauti- 

 ful objects when denuded of flesh ! 



THE editor of this edition would, as in the case 

 of the Branch of the Animal Kingdom II., Porifer- 

 a(a, treat of the First Branch where, according to 

 late authorities, it properly belongs. For classi- 

 fication and nomenclature, according to modern 

 authors, see tables of Smithsonian Institution. 



Branch I. PROTOZOA. First animals, is meant 

 literally or, looking at animal life in a descending 

 series the last, or lowest of animals. In our pages 

 this latter view is adopted. 



The simplest object that can be called an ani- 

 mal is embraced in this branch. All of this group 

 can move, eat, and reproduce their kind. They 

 move by little oars placed in all parts of the 

 exterior ; they eat by absorbing minute animal and 

 vegetable substance into all parts of their bodies ; 

 and they are reproduced by the division of their 

 forms indefinitely. Such creatures, we are ready 

 to understand from their composition, are formed 

 of single cells, whose parts are homogeneous, one 

 bit being a representation of another or the whole. 



The Protozoa are mostly minute creatures 



microscopic. There is some degree of rank observed among the Protozoa. The first class 

 embraces the lowest, called Monera. One of these forms, called Protomyxa, is regarded as 

 the simplest representative. 



The RTiizopods form a second class, but the differences are extremely small. 



The fresh-water Rhizopods of America have been treated in a magnificent work, with 

 colored plates. In the first Order of this class, the well-known Amceba is placed. See the 

 figure in accompanying engraving. 



VOL. m. 75. 



GLASS VASE. Euplectella aspergUlum. (Two-th.iUi. 

 natural size.) 



