GLOSSARY 



Acanthias (Gr. acantha, spine) : a genus of sharks including the spiny dogfish, 

 so named from the spines on the dorsal fins. 



Acanthopterygii (Gr. acantha, spine ; pterux, wing or fin) : fishes with 

 spinous rays supporting the paired fins, e.g. perch. 



Acarina (Gr. akari, mite) : a division of the Arachnida, of which the cheese- 

 mite is a type. 



Acilius caliginosus : a beetle belonging to the family Dyticidas, Order Cole- 

 optera. 



Acipenser (L. — a large fish commonly taken to be sturgeon) : genus of Ganoids 

 including the sturgeon. 



Acone eyes (Gr. a, without ; konos, cone) : retina; of invertebrate animals in 

 which there are no crystalline cones, as in many insects, e.g. Coleoptera, 

 Diptera. 



Actinozoa (Gr. actin, ray ; zodn, animal) : a division of the Coelenterata, of 

 which the sea-anemones are a type, and which show a radial symmetry. 



Adiadochokinesia (Gr. a, absence of; diadoche, succession; kinesis, move- 

 ment) : inability to perform successive movements, such as rapid and 

 repeated pronation and supination of the two forearms. 



Agelena labyrinthica : a cellar spider belonging to the Order Araneida. 



Agnathi (Gr. a, without ; gnathos, jaw) : the branch of craniate vertebrates 

 which includes the Ostracodermi or Cyclostomata and characterized by 

 the absence of jaws. 



Amblystoma (Gr. amblus, blunt ; stoma, mouth) : a tailed amphibian, the per- 

 manent larval form of which is the Mexican Axolotl, having a blunt nose. 



Ami a (Gr. amia, a kind of tunny) : a bony fish allied to the mackerels. 



Ammoccetes (Gr. ammos, sand ; ketos, fish) : the larval form of Petromyzon, 

 lamprey. 



Ammonites (Gr. ammon, (ram's) horn, symbol of Zeus-Ammon) : the fossil 

 shells of the extinct Cephalopoda, usually referred to the subclass 

 Tetrabranchiata. Their spiral shells resemble that of the living genus 

 Nautilus. 



Amphioxus (Gr. amphi, both ; oxus, sharp) : the lancelet fish, so named on 

 account of its being pointed at both ends. It belongs to the subclass 

 Cephalochorda. 



Amphipoda (Gr. amphi, both ; pons, foot) : an order of the Crustacea, com- 

 prising the sand-hoppers and fresh- water shrimps. The feet are directed 

 both forwards and backwards. 



Anapsida (Gr. a, an, without ; apsis, arch) : the name applied to a primitive 

 type of reptile in which the roof of the skull is complete, without a 

 temporal fossa, as in the Stegocephala. See : Synapsida ; Diapsida. 



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