OF CONCHOLOGY. 131 



/9. Living in herds ; polygamous (Ruminantia, Gallinacea). 



0. Living together in colonies bound together by instinct. The 

 nursing of the young and the defence of the colony is often pur- 

 veyed by a sexual individual, which seems to indicate a defective 

 organization of the sexual individuals (Hymenoptera). 



}'. Thytoid colonies, composed of individuals united together 

 bodily, and performing various duties ; feeding, generating, de- 

 fence. 



e. Colonies in which some of the individuals are reduced to 

 organs : Zoites, Zonites, Duges,* Taeniae, Hydrge, Worms, 

 Acephala. 



XVII. According to the form of the body, L. Glaserf has 

 distinguished two principal forms : involute animals (as Mam- 

 malia, Reptilia, MoUusca), and evolufe animals [as Birds, Fishes, 

 Insects, Zoophytes). The classes of the former division are al- 

 ways the highest in their respective series, although they exter- 

 nally are of less importance in appearance. The Mole, e. g., 

 looks externally more degenerated than any bird. The same is 

 to be observed relative to Coecilia and Amphisboena, in opposi- 

 tion to Fishes. 



1. Latero symmetrical animals, with the intestinal generative 

 openings in the median line. Vertebrata, Insecta, Crustacea, 

 Acephala, Cephalopoda, Chitons, have lateral generative open- 

 ings. All spiral Mollusca have the anus, urethral, generative 

 and respiratory openings lateral, except Onchis, which have only 

 the male organ lateral. 



DanaJ has formed the following nomenclature, according to 

 the position of the locomotive organs : Prosthenic (Birds, Hy- 

 menoptera, Lepidoptera) ; Methasthenic (gallinaceous Birds, 

 Coleoptera) ; Urosthenic (Thysanura). 



2. Radiated animals are — 



a. Free (Anthoidea), in most directions symmetrical (Medusa), 

 or only apparently radiated symmetrical : Echinodermata, 

 Cephalopoda. 



p. Dendroid or phytoid forms are always aquatic. 



XVlII. According to size, the higher animals offer the largest 

 individuals, and never so minute as the lower ; but the largest- 

 species are never the highest in rank in their respective classes. 

 Aquatic and paludestrine animals are always larger than terres- 

 trial or arboreal. Insectivora and Carnivora can never reach 



* Conformites Organiques Lam., ed. 2, p. 53. 



t L. Glaser, Isis, 1842, p. 6. 



t Dana, Am. Journ. of Science, 1863, p. 321. 



