684 - Appendix J 



endoskeleton of calcareous ossicles and 

 spines; unique water vascular system; with 

 tube feet. (5000 species.) 



Class Crinoidea: feather stars; sessile ani- 

 mals often having a jointed stalk for attach- 

 ment. 



Class Asteroidea: starfishes. 



Class Ophiuroidea: brittle stars. 



Class Echinoidea: sea urchins. 



Class Holothiiroidea: sea cucumbers. 



Phylum CHORDATA: animals having at 

 some stage a notochord, gill slits, and a hol- 

 low nerve cord on the dorsal side. (60,000 

 species.) 



Subphylum hemichordata: the acorn, or 

 proboscis worms; wormlike animals with a 

 notochordlike structure in the head end. 



Subphylum urochordata: tunicates, or 

 sea squirts; saclike, usually sessile animals, 

 often forming branching colonies; in the 

 larval stage they have a notochord in the tail 

 region. 



Subphylum cephalochordata: lancelets; 

 somewhat fishlike animals, with a permanent 

 notochord the whole length of the body; no 

 cartilage or bone. 



Subphylum vertehrata: the vertebrates; 

 notochord surrounded or replaced by carti- 

 lage or bone, forming the vertebral column 

 or backbone. 



Class Cyclostomata: lampreys and hag- 

 fishes, eellike vertebrates, without limbs or 

 jaws. 



Class Chondrichthyes: sharks, rays, skates, 

 and other cartilaginous fish; without air blad- 

 ders. 



Class Osteichthyes: the bony fish, including 

 crossopterygians, dipnoians, and ganoids, 

 which are almost extinct; usually with an air 

 bladder or (rarely) a lung. 



Class Amphibia: salamanders, frogs, and 

 toads; usually breathing by gills in the larval 

 stage, by lungs in the adult stage; incomplete 

 double circulation; skin usually naked; the 

 limbs are legs. 



Class Reptilia: turtles, li/ards, snakes, croco- 

 diles; breathing by lungs; incomplete double 



circulation; skin usually covered with scales; 

 the limbs are legs (absent in snakes). 



Class Aves: the birds; warm-blooded ani- 

 mals with complete double circulation, skin 

 covered with feathers, the forelimbs wings. 



Class Mammalia: the mammals; warm- 

 blooded animals with complete double cir- 

 culation, skin usually covered with hair, 

 young nourished with milk secreted by the 

 mother; limbs usually legs (forelimbs some- 

 times arms, wings, or fins). 



Subclass Prototheria: the monotremes; 

 oviparous mammals with imperfect tempera- 

 ture regulation; only two living species, the 

 duckbill and spiny anteater of Australia. 



Subclass Metatheria: the marsupials; vivip- 

 arous mammals without a placenta (or with 

 a poorly developed one), the young carried 

 in an external pouch of the mother for some 

 time after birth; kangaroos, opossums, etc. 



Subclass Eutheria: mammals with a well- 

 developed placenta, comprising the great ma- 

 jority of living mammals. The principal 

 orders of Eutheria are the following: 



Inscctivora: shrews, moles, hedgehogs, etc. 



Edentata: toothless mammals; anteaters, 

 sloths, armadillos, etc. 



Rodcntia: the rodents; rats, mice, squir- 

 rels, etc. 



At tiodactyla: even-toed ungulates; cattle, 

 deer, camels, hippopotamuses, etc. 



Pei issodactyla: odd-toed, hoofed mammals; 

 horses, zebras, rhinoceroses, etc. 



Proboscidea: elephants. 



Lagomorpha: rabbits and hares. 



Sirenia: the manatee, dugong, and sea 

 cows; large aquatic mammals with the fore- 

 limbs finlike, the hind limbs absent. 



Carnwora: carnivorous animals; cats, dogs, 

 bears, weasels, seals, etc. 



Cctacea: the whales, dolphins, and por- 

 poises; aquatic mammals with the forelimbs 

 fins, the hind limbs absent. 



Cliiroptera: the bats, aerial mammals with 

 the forelimbs wings. 



Primates: the lemurs, monkeys, apes, and 

 man. 



