GLOSSARY. 



ABDOMEN (Lat. abdo, I conceal). The posterior cavity of the body, contain- 

 ing the intestines and others of the viscera. In many Invertebrates there 

 is no separation of the body-cavity into thorax and abdomen, and it is only 

 in the higher Annulosa that a distinct abdomen can be said to exist. 



ABERRANT (Lat. aberro, I wander away). Departing from the regular type. 



ABNORMAL (Lat. ab, from ; norma, a rule). Irregular ; deviating from the 

 ordinary standard. 



ABOMASUM. The fourth cavity of the complex stomach of the Kuminants. 



ABRANCHIATE (Gr. a, without ; bragchia, gills). Destitute of gills or bran- 

 chiae. 



ACALEPEUE (Gr. akalepJie, a nettle). Applied formerly to the Jelly-fishes or 

 Sea-nettles, and other Radiate animals, in consequence of their power of 

 stinging, derived from the presence of microscopic cells, called " thread- 

 cells," in the integument. 



ACANTHOCEPHALA (Gr. acantha, a thorn ; kephale, head). A class of parasitic 

 worms in which the head is armed with spines. 



ACANTHOMETRINA (Gr. akantha ; and metra, the womb). A family of Protozoa, 

 characterised by having radiating silicious spines. 



ACANTHOPTERYGIA (Gr. akantha, spine; pterux, wing). A group of bony 

 fishes with spinous rays in the front part of the dorsal fin. 



ACARINA (Gr. akari, a mite). A division of the Arachnida, of which the 

 Cheese-mite is the type. 



ACEPHALOUS (Gr. a, without ; kephale, head). Not possessing a distinct head. 



ACETABULA (Lat. acetabulum, a cup). The suckers with which the cephalic 

 processes of many Cephalopoda (Cuttle-fishes) are provided. 



ACETABULUM. The cup-shaped socket of the hip-joint in Vertebrates. 



ACRITA (Gr. akritos, confused). A term sometimes employed as synony- 

 mous with Protozoa, or the lowest division of the animal kingdom. 



ACTINOMERES (Gr. aktin, a ray ; meros, a part). The lobes which are mapped 

 out on the surface of the body of the Ctenophora, by the ctenophores, or 

 comb-like rows of cilia. 



ACTINOSOMA (Gr. aktin; and soma, body). Employed to designate the 

 entire body of any Actinozob'n, whether this be simple (as in the Sea- 

 anemones), or composed of several zooids (as in most Corals). 



ACTINOZOA (Gr. aktin ; and zoon, an animal). That division of the Ccelen- 

 terata of which the Sea-anemones may be taken as the type. 



ADELARTHROSOMATA (Gr. adelos, hidden; arthros, joint; soma, body). An 

 order of the Arachnida. 



AGAMIC (Gr. a, without ; gamos, marriage). Applied to all forms of repro- 

 duction in which the sexes are not directly concerned. 



ALLANTOIDEA. The group of Vertebrata in which the foetus is furnished with 

 an allantois, comprising the Reptiles, Birds, and Mammals. 



ALLANTOIS (Gr. alias, a sausage). One of the "membranes" of the foetus in 

 certain Vertebrates. 



