GLOSSARY 481 



Anaspida (Gr. a, an, without ; aspis, shield) : an order of extinct fishes belong- 

 ing to the branch Ostracodermi, characterized by the absence of a head- 

 shield. 



Anguis fragilis (L. anguis, snake ; fragilis, brittle) : blindworm, a snake-like, 

 limbless lizard with imperfectly developed eyes. 



Annelida (Gallicised form of Annulata) : ringed worms, without jointed feet, 

 and comprising the sub-classes Chaetopoda and Hirudinea. 



Annulosa (L. annuhts, ring) : sub-kingdom comprising the Anarthropoda and 

 Arthropoda in which the body consists of a succession of rings. 



Anomodontia (Gr. anomos, without order or irregular ; odous, tooth) : an 

 extinct order of reptiles, also called Dicynodontia, with large teeth 

 resembling a dog's canines. 



Anoura (Gr. a, an, without ; oura, tail) : tailless amphibia, e.g. frogs and toads. 



Apus Cancriformis (Gr. a, without ; pons, foot ; L. cancer, crab ; forma, 

 shape) : a small fresh-water crustacean characterized by a dorsal shield 

 and crab-like form. 



Arachnida (Gr. arachne, web ; arachnes, spider) : air-breathing Arthropoda, 

 including the spiders and scorpions. 



Argonauta (Gr. argos, living without labour ; naute, sailor) : the female 

 " paper nautilus," a dibranchiate cephalopod, with a corrugated spiral 

 shell in which the animal floats idly on the surface of the water. 



Argulus : the carp louse, an external parasitic Copepod, crustacean, having 

 a trilobate median eye and compound lateral eyes. 



Arthrodira (Gr. arthron, joint ; deire, neck) : an order of extinct fishes 

 including Coccosteus, Dinichthys, and Titanichthys ; they are 

 characterized by a joint separating the head-shield from the body-shield. 



Arthropoda (Gr. arthron, joint ; pons, foot) : an invertebrate phylum char- 

 acterized by jointed limbs, as contrasted with " bristle " feet. 



Ascidia (Gr. askos, bottle ; eidos, like) : an order of the class Tunicata, with 

 sac-like bodies, comprising the sea-squirts. 



Ascidia mammillata (Gr. askos, bottle ; eidos, shape) : a Tunicate the free- 

 swimming larva of which contains a single eye enclosed within the 

 ventricular cavity of the brain. 



Astacus fluviatilis : fresh-water crayfish, belonging to the order Decapoda 

 of the class Crustacea. 



Astroscopus (Gr. astron, stars ; skopeo, look) : the American star-gazer. An 

 electric ray in which the eyes are situated close together and directed 

 upwards. The electric organs are on the dorsal surface of the head 

 just behind the eyes. 

 Auchenaspis (Gr. auchen, narrow, neck ; aspis, shield) : an extinct palaeozoic 

 fish belonging to the class Ostracodermi. It had paired lateral orbital 

 cavities, between which are two small pineal canals. 

 Aurelia aurita (L. aureolns, golden colour ; anrita, long-eared) : the common 

 jelly-fish, so named on account of its colour and the ear-shaped form of 

 its oral arms. 

 Axolotl : the persistent larva of Amblystoma, which retains its external 

 branchiae throughout life. 

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