GLOSSARY. 573 



ALVEOLI (Lat. dim. of alvus, belly). Applied to the sockets of the teeth. 



AMBULACRA (Lat. ambulacrum, a place for walking). The perforated spaces 

 or " avenues" through which are protruded the tube-feet, by means of 

 which locomotion is effected in the Mchinodermaia. 



AMBULATORY (Lat. ambulo, 1 walk). Formed for walking. Applied to a 

 single limb, or to an entire animal. 



AMETABOLIC (Gr. a, without ; metabole, change). Applied to those insects 

 which do not possess wings when perfect, and which do not, therefore, 

 pass through any marked metamorphosis. 



AMNION (Gr. amnos, a lamb). One of the foetal membranes of the higher 

 Vertebrates. 



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

 amnion, comprising the Reptiles, Birds, and Mammals. 



AMCEBA (Gr. amoibos, changing). A species of Rhizopod, so called from the 

 numerous changes of form which it undergoes. 



AMCEBIFORM. Resembling an Amoeba in form. 



AMORPHOZOA (Gr. a, without ; morphe, shape ; zoon, animal). A name some- 

 times used to designate the Sponges. 



AMPHIBIA (Gr. amphi, both ; bios, life). The Frogs, Newts, and the like, 

 which have gills when young, but can always breathe air directly when 

 adult. 



AMPHICCELOUS (Gr. ampki, at both ends ; Jcoilos, hollow). Applied to verte- 

 brae which are concave at both ends. 



AMPHIDISCS (Gr. amphi, at both ends ; diskos, & quoit, or round plate). The 

 spicula which surround the gemmules of Spongilla, and resemble two 

 toothed wheels united by an axle. 



AMPHIOXUS (Gr. amphi, at both ends ; oxus, sharp). The Lancelet, a little 

 fish, which alone constitutes the order Pharyngobronchii. 



AMPHIPNKUSTA (Gr. amphi, both ; pneo, I breathe). Applied to the "peren- 

 nibranchiate" Amphibians which retain their gills through life. 



AMPHIPODA (Gr. amphi, and pous, a foot). An order of Crustacea. 



ANAL (Lat. anus, the vent). Connected with the anus, or situated near the 

 anus. 



ANALLANTOIDEA. The group of Vertebrata in which the embryo is not fur- 

 nished with an allantois. 



ANALOGOUS. Applied to parts which perform the same function. 



AN AMNIOTA. The group of Vertebrata in which the embryo is destitute of an 

 amnion. 



ANARTHROPODA (Gr. a, without ; arthros, a joint ; pous, foot). That division of 

 Annulose animals in which there are no articulated appendages. 



ANCHYLOSIS or ANKYLOSIS (Gr. ankulos, crooked). The union of two bones 

 by osseous matter, so that they become one bone, or are immovably joined 

 together. 



ANDROGYNOUS (Gr. aner, a man ; gune, a woman). Synonymous with her- 

 maphrodite, and implying that the two sexes are united in the same in- 

 dividual. 



ANDROPHORES (Gr. aner, a man ; and phero, I carry). Applied to medusiform 

 gonophores of the Hydrozoa, which carry the spermatozoa, and differ in 

 form from those in which the ova are developed. 



ANNELIDA (a Gallicised form of Annulata). The Ringed worms, which 

 form one of the divisions of the Anarthropoda. 



ANNULATED. Composed of a succession of rings. 



ANNULOIDA (Lat. annul us, a ring ; Gr. eidos, form). The sub-kingdom com- 

 prising the Echinodermata and the Scolecida (=Echinozoa). 



ANNULOSA (Lat. annulus). The sub-kingdom comprising the Anarthropoda 

 and the Arthropoda or Articulata, in all of which the body is more or less 

 evidently composed of a succession of rings. 



ANOMODONTIA (Gr. anomos, irregular; odous, tooth). An extinct order of 

 Reptiles, often called Dicynodontia. 



ANOMURA (Gr. anomos, irregular ; oura, tail). A tribe of Decapod Crustacea, 

 of which the Hermit-crab is the type. 



