SERIAL CONNECTION AMONG ANIMALS. 69 



presence, but also that of time, which involves prescience. 

 The series of Crinoids, that of Brachiopods through all 

 geological ages, that of the Nautiloids, that of Ammoni- 



O <D o 



toids from the Triassic to the Cretaceous formations inclu- 

 sive, that of Trilobites from the lowest beds up to the 

 Carboniferous period, that of Ganoids through all the for- 

 mations ; then, again, among living animals in the class of 

 Mammalia, the series of Monkeys of the Old World espe- 

 cially, that of Carnivora, from the Seals through the Plan- 

 tigrades to the Digitigrades ; in the class of Birds, that 

 of the Wading Birds, and that of the Gallinaceous Birds ; 

 in the class of Fishes, that of Pleuronectids and Gadoids, 

 that of Skates and Sharks ; in the class of Insects, that of 

 Lepidoptera from the Tineina to the Papilioiiina ; in the 

 class of Crustacea, that of the Decapods in particular ; in 

 the class of Worms, that of the Nudibranchiata and that of 

 the Dorsibranchiata especially ; in the class of Cephalo- 

 poda, that of the Sepioids ; in the class of Gasteropoda, 

 that of the Nudibranchiata in particular ; in the class of 

 Acephala that of the Ascidians and that of the Oysters in 

 the widest sense ; in the class of Echinoderms, those of the 

 Holothurians and Asterioids ; in the class of Acalephs, that 

 of the Hydroids ; in the class of Polyps, that of the Hal- 

 cyonoids, of the Atroeoids, etc., etc., deserve particular 

 attention, and may be studied with great advantage in 

 reference to the points under consideration. For every- 

 where do we observe in them, with reference to space and 

 to time, the thoughtful combinations of an active mind. 



o 



But it ought not to be overlooked, that, while some types 

 represent strikingly connected series, there are others in 

 which nothing of the kind seems to exist, and the diver- 

 sity of which involves other considerations. 



