OUTLINES OF THE ANIMAL KINGDOM. 105 



divided, and all rearranged, in other or new subkingdoms. The Echinoder- 

 mata are otherwise unchanged. The Intestina are associated with certain 

 minute marine worms, and with the rotiferous animalcules from Cuvier's In- 

 fusoria, to form a class named Scolecida, placed next below the true worms or 

 Annelida. The Acalepha are made to form part of the new class Hydrozoa. 

 The Polypi are split up and separated in three directions ; the order of coral- 

 line polyps form the class Polyzoa (sometimes named the Bryozoa) ; the order 

 Actinia or sea-anemones becomes the class Actinozoa ; whilst the order of 

 gelatinous polyps, represented by the hydra, is united with the Acalepha in 

 the class Hydrozoa. Lastly, of the Infusoria of Cuvier, one order, the Roti- 

 fera, passes upwards to join, as already mentioned, the Scolecida ; whilst the 

 others form the present Infusoria, after discarding certain algaceous vegetable 

 organisms ; finally, certain remaining lowly organized animal bodies consti- 

 tute the new classes Spongida, Rhizopoda, and Gregarinida. 



Such being the modifications in those carefully defined groups which consti- 

 tute the classes of the animal kingdom, we may now direct attention to the 

 resulting changes in the larger groups or subkingdoms. The Vertebrate sub- 

 kingdom remains intact. The Mollusca of Cuvier, diminished by the Cirrho- 

 pods, which pass into the Crustacea of another subkingdom, and increased 

 by the Polyzoa, the radiate coralline polyps of Cuvier, present the same gene- 

 ral limits as the two subkingdoms, Mollusca and Molluscoida, of the new 

 arrangement, the line of partition between these latter being drawn between 

 the Lamellibranchiata and Ascidioida, i. e., through the centre of the Aceph- 

 alous Molluscs of Cuvier. The Articulate subkingdom of the French zoologist 

 remains undivided, as the Annulosa, reinforced only by the Cirrhopods, which, 

 as just stated, are now included in the Crustacea. The Radiate subkingdom, 

 corresponding, it may be remarked, with the so-called Zoophytes of many 

 writers, disappears ; for its classes are completely broken up and distributed 

 into other or new subkingdoms. Thus, the coralline polyps are transferred to 

 the new subkingdom Molluscoida, and form the lowest Molluscoid class. The 

 new subkingdom Annuloida includes the Echinodermata, with the Intestina 

 and rotiferous order of the Infusoria, the two latter being joined under the 

 name Scolecida. The new subkingdom, named Coalenterata, comprehends a 

 second group of the polypi, namely, the Actinia, under the title Actinozoa, 

 and also the gelatinous polypi, which, with the Acalepha, form the Hydrozoa. 

 Lastly, the new subkingdom Protozoa includes the Infusoria, with the excep- 

 tion of the Rotifera, which ascend to the Annuloid subkingdom, and also the 

 three lowest new classes, the Spongida, Rhizopoda, and Gregarinida. 



The preceding changes are due to the labors of many zoologists. Thus, 

 Carus suggested the term Protozoa, whilst Yon Siebold and his followers 

 separated that group into a distinct subkingdom. The Coelenterate subking- 

 dom and its limits were suggested and defined by Frey and Leuckart. The 

 Molluscoid and Annuloid subkingdoms owe their origin to Milne-Edwards 

 and Huxley, the coralline polyps, or Polyzoa, especially, having been placed 

 in their new position owing to the researches of the former naturalist. The 

 Cirrhopods were long since transferred to the Crustacea by Grant ; and the 

 Intestina have, by many authors, been removed to the neighborhood of the 

 true worms. With regard to the worms, some zoologists, as, e. (/., Gegen- 

 bauer, have even placed them in a distinct subkingdom named Vermes ; whilst 

 the Echinodermata have also received similar treatment. Even the Infusoria, 

 as already mentioned, have been separated from the other Protozoa as if form- 

 ing a group of higher importance than a mere class (Huxley). The general 

 relations between the subkingdoms of the Cuvierian and of the modified ar- 

 rangement here adopted may be expressed by the following schemes : 



