GLOSSARY 



^ Abdomen (Lat. dido, I conceal) In Mammalia, that part of the 



body cavity Which is separated from the thorax or chest by 



the diaphragm. 

 Acalepha (Gr. akakplie, a nettle) Jelly fishes or sea-nettles, so 



called on account of their ability to sting by means of 



"thread cells." 

 Acanthocephala (Gr. acanthos, a thorn ; kepliale, the head) A 



group of internal parasites, so called because the head is 



armed with spines. 

 Acephalous (Gr. a, without ; kepJiak, the head) Without a 



distinct head. The Lamellibranchiata are sometimes called 



Acephala. ' 

 Actinosoma (Gr aktis, a ray ; soma, body) A term applied to 



the whole body of an actinozoon, whether simple or com- 

 pound. 

 Actinozoa (Gr. dktis, a ray ; zoon, an animal) A class of 



ccelenterata. 

 Albumen (Lat. albus, white) A substance resembling the white 



of an egg. 

 Alimentary Canal (Lat. alo, I nourish) The tube through which 



the food passes. 

 ^ Allantois (Gr. alias, a sausage) A foetal membrane in mammals, 



birds, and reptiles. 

 Ambulacra (Lat. ambulacrum, a garden walk) The spaces in the 



tests of sea-urchins and star-fishes, containing the apertures 



through which the "tube feet" are protruded. 

 Ametabolic (Gr. a, without; metabole, change) A term applied to 



those insects which do not undergo metamorphosis. 

 Ammonites (so called from their resemblance to the horns on the 



statues of Jupiter- Ammon) A group of extinct chambered 



shells belonging to the class Cephalopoda. 

 t^Amnion (Gr. amnos, a lamb) A fcetal membrane in mammals, 



birds, and reptiles. 

 Amoeba (Gr. amoibe, a change) One of the Rldzopoda, which 



constantly changes its shape. 

 ^Amphibia (Gr. amphi, both ; bios, life) A class of Vertebrata 



adapted for breathing in water when young, and in air when 



mature. The terin was formerly applied to aquatic mammals, 



such as the seals, 



