366 PRINCIPLES OF ANIMAL BIOLOGY 



plants. It more commonly deals with the grosser features, but the finest details of 



structure are not excluded. 

 Anaximander {an aks' i vian der). A Greek physical philosopher and mathematician, 



pupil of Thales, who lived about 611-547 B. C. 

 Anguis {ang' gvyis). A genus of legless lizards. 



Animal pole {an' i vial ■pole'). That part of an egg in which the protoplasm is con- 

 centrated (in eggs with much yolk), and which in most animals produces the 

 nervous system, sense organs, etc. Other features may also characterize the 

 animal pole. 



Anisogamy {an' i sog' a mi). Fusion of unlike gametes in reproduction. 



Annelida {anneV ida). The phylum of animals comprising the segmented worms. 

 For definition see Chapter XII. 



Anodonta {an' o don' ta). A genus of freshwater mussels. 



Anodontoides {an' o don toi' deez). A genus of freshwater mussels. 



Antenna {an ten' na){pl., antennae). One of a pair of jointed appendages project- 

 ing forward from the head of an insect or crustacean. 



Anthocystis {an' tho sis' tis). A genus of rhizopod Protozoa, of the order HeUozoa. 



Anthophysa {an' tho fi' za) . A genus of colonial flagellate Protozoa whose cells are 



borne in radiating masses on a branching stalk. 

 Anthothrips niger {an' tho thrips ni' jer). A species of insect of the order Thysan- 



optera, commonly called thrips. 

 Anthozoa (an' tho zo' a). A class of Ccelenterata, comprising the sea anemones and 



mo.st of the corals. They have no medusoid form in the life cycle. 

 Anthropoid {an' thro poid). Man-like; said of certain apes. 

 Antimere {an' ti rneer). One of a series of parts, radially arranged like the spokes of 



a wheel. 

 Ant-lion {anf li' on). An insect whose larva lives in a conical pit dug in the sand, 



capturing other insects that fall into the pit. 

 Anus {a'nus). The posterior opening of the digestive tract. 



Apoda {ap' o da). An order of Amphibia comprising the legless forms called ccecilians. 

 Appendicular skeleton {ap'pen dik' u ler). The bones of the limbs and their attaching 



girdles in vertebrates. 

 Arachnida {arak' nida). A class of Arthropoda comprising the spiders, scorpions 



and mites. For definition see Chapter XII. 

 Archaeopteryx {ar' he op' ter iks). An extinct animal of Jurassic time resembling both 



reptiles and birds, having teeth and feathers. 

 Archaeozoic {ar' ke o zo' ik) . Of the earliest geological period; the oldest known 



system of rocks is of this period, 

 Archenteron {ark en' ter on). The cavity within the endoderm of a gastrula. It 



communicates with the exterior. 

 Archiannelida {ar' li anneV i da). A class of primitive marine worms (Annelida) 



without setae. 

 Aristotle {ar' is tot'l). The most famous of the Greek naturalist philosophers, who 



lived 384-322 B.C. 

 Armadillo {ar' ma diV lo) . An armored mammal of the order Edentata, which 



includes also the sloths and ant-eaters. 

 Artery {ar' te ri). A blood vessel conducting blood from the heart. 



