702 SCIENTIFIC RECREATIONS. 



BRANCH III. ARTICULATA. 



Class I. Worms, . 3 orders . trematods (including leeches, etc.), nematoids, 



and annelides. 



II. Crustacea . 4 , rotifera,crinopods,tetradecapods, and decapods. 

 III. Insects. . 3 . myriapods, arachnoids, and insects proper. 



BRANCH IV. VERTEBRATA. 



Class I. Myzontes . 2 orders . myxinoids and cyclostomes. 

 II. Fishes proper. 



III. Ganoids . 3 caelacanths, axipenseroids, and sauroids. 



IV. Selachians . 3 chimrerae, galeodes, and batides. 



V. Amphibians . 3 . caeciliae, ichthyodi, and anoura. 



VI. Reptiles . . 4 . serpents, saurii, rhizodontes, and testudinata. 



VII. Birds . . 4 . natatores, grallae, rasores, and incessores. 



W VIII. Mammalia . 3 . marsupiaia, herbivora, and carnivora. 



In the vertebrated animals the blood is red in consequence of the 

 minute cells (corpuscles) which contain the colouring matter. In invertebrate 

 animals these red cells are absent, and so the animals are white-blooded. 

 Some animals, again, are cold-blooded like the fish ; birds and mammalia 

 have warm blood. It is worthy of remark that the higher we advance in 

 the scale the fewer the offspring of the animal. The animalcules multiply at 

 the rate of many billions a day, and even one codfish is stated to contain 

 more than nine millions of eggs. A mackerel will produce 500,000; and so 

 on, as we rise, we find mammals with seldo.m more than ten young at a time, 

 down to one single offspring. 



We could fill pages with the account of the differences existing between 

 animals created for such different purposes and fitted to inhabit different 

 climates, their mode of feeding and catching prey. The manner of bringing 

 forth and rearing the young, and the temperament and temper of the 

 animal creation would fill a volume, but we cannot now stay to examine 

 these various characteristics. The following is the arrangement now 

 usually adopted ; 



NICHOLSON. 

 INVERTEBRATES. 



PROTOZOA. 

 The lowest forms of animal life microscopic animah. 



Gregarinida . Cell forms ; worm-like. 



Rhizopoda . Amebas, foraminifera, radiolaria, sponges. 



Infusoria . Suctoria, ciliata, etc. 



* 



C/ELENTERATA (THE OLD RADIATA). 



HYDROZOA. 

 Intermediary^ having a mouth and receptacle separated by no alimentary canal. 



Polypes and Zoophytes, Actinozoa. . Medusae, millipores, corals, sea-anemones, tubipora, 



siphonophera, etc. 



