790 GLOSSARY. 



ASTEROID (Gr. aster, a star ; and eidos, form). Star-shaped, or possessing radi- 



iug lobes or rays like a star-fish. 



ASTEROIDEA. An order of Echinodermata, comprising the Star-fishes, char- 

 acterised by their rayed form. 



ASTOMATOUS (Gr. a, without ; stoma, mouth). Not possessing a mouth. 

 ATLAS (Gr. the god who holds up the earth). The first vertebra of the neck, 



which articulates with and supports the skull. 

 ATRIUM (Lat. a hall). Applied to the great chamber or " cloaca," into which 



the intestine opens in the Tunicata. 

 AURELIA (Lat. aurum, gold). Applied to the chrysalides of some Lepidoptera, 



on account of their exhibiting a golden lustre. 

 AURICLE (Lat. dim. of auris, ear). Applied to one of the cavities of the heart, 



by which blood is driven into the ventricle. 

 AUTOPHAGI (Gr. autos, self ; phago, I eat). Applied to birds whose young 



can run about and obtain food for themselves as soon as they escape from 



the egg. 



AVES (Lat. avis, a bird). The class of the Birds. 

 AVICULARIUM (Lat. avicula, dim. of avis, a bird). A singular appendage, 



often shaped like the head of a bird, found in many of the Polyzoa. 

 Axis (Gr. axon, a pivot). The second vertebra of the neck, upon which the 



skull and atlas usually rotate. 

 AZYGOUS (Gr. a, without ; zugon, yoke). Single, without a fellow. 



BACTERIUM (Gr. bakterion, a staff). A microscopic organism occurring in fluids 

 containing organic matter, and having a staff-shaped form. 



BALANID.E (Gr. balanos, an acorn). A family of sessile Cirripedes, commonly 

 called "Acorn shells." 



BALEEN (Lat. balcena, a whale). The horuy plates which occupy the palate of 

 the "whalebone" Whales. 



BATIDES (Gr. batos, a bramble). The family of the Elasmobranehii comprising 

 the Bays. 



BATRACHIA (Gr. batrachos, a frog). Often loosely applied to any of the Am- 

 phibia, but sometimes restricted to the Amphibians as a class, or to the 

 single order of the Anoura. 



BELEMNITIDJ;! (Gr. belemnon, a dart). An extinct group of Dibranchiate Cepha- 

 lopods, comprising the Belemnites and their allies. 



BICAVITART (Lat. fris, twice ; cavus, hollow). Consisting of or possessing two 

 cavities. 



BIFID. Cleft into two parts ; forked. 



BILATERAL. Having two symmetrical sides. 



BIMANA (Lat. bis, twice ; manus, a hand). The order of Mammalia compris- 

 ing Man alone. 



BIPEDAL (Lat. bis, twice ; pes, foot). Walking upon two legs. 



BIRAMOUS (Lat, bis, twice ; ramus, a branch). Applied to a limb which is 

 divided into two branches (e.g., the limbs of Cirripedes). 



BIVALVE (Lat. bis, twice ; valvce, folding-doors). Composed of two plates or 

 valves ; applied to the shell of the Lamellibranchiata and Brachiopoda, and 

 to the carapace of certain Crustacea. 



BLASTOIDEA (Gr. blastos, a bud ; and eidos, form). An extinct order of Echi- 

 nodermata, often called Pentremites. 



BLASTOSTYLE (Gr. blastos, a bud ; and stulos, a column). Applied by Prof. 

 Allman to certain columniform zob'ids in the Hydrozoa which are destined to 

 bear generative buds. 



BRACHIOPODA (Gr. brachion> an arm ; pous, the foot). A class of the Mol- 

 luscoida, often called " Lamp-shells," characterised by possessing two fleshy 

 arms continued from the sides of the mouth. 



BRACHIUM (Gr. brachion, arm). Applied to the upper arm of Vertebrates. 



BRACHYURA (Gr. brachus, short ; oura, tail). A tribe of the Decapod Crusta- 

 ceans with short tails (i.e., the Crabs). 



BRACTS. (See Hydrophyllia). 



BRADYPODIDJE (Gr. bradus, slow ; podes, feet). The family of Edentata, com- 

 prising the Sloths. 



