[7] 



peculiar little animal was a lancet-shaped marine worm, akin to the 

 lancelet or amphioxus of to-day. From these developed Monorrhini, or 

 vetebrate hybrid worms and fishes, with skull, brain, and central heart, 

 but no sympathetic system, jaws, or limbs, and with a single nasal cavity 

 (lampreys). These three forms are placed in the Silurian period, in 

 which stratum have been found fossilised bony plates and scales of fishes 

 and Annelides, or sea-worms. 



The next forms of life to be developed, from the Monorrhini, were 

 the Selachii (Amphirrhini), or true fishes, of the shark family, with 

 two nasal cavities, swim-bladder, two pairs of fins, and jaws. From 

 these evolved the Ganoidei, and thence all osseous fishes ; and Dipnoi 

 (mud fish), or hybrid fishes and amphibians, with both gills and 

 lungs. These little animals live during winter in water, when they 

 breathe air dissolved in water through their gills ; and during the 

 summer in mud, when they breathe with their lungs. Both these 

 are placed in the Devonian period, in which have been found 

 fossil sharks, etc. The next forms are Sozobranchii, or amphibians with 

 persistent gills, from which evolved Urodela, or amphibians with transitory 

 gills, but persistent tails, and legs ; allied to the salamander. These are 

 placed in the Carboniferous period, in which have been found fossilised 

 amphibians. We next get Protamnia, or hybrid salamanders and lizards 

 (frogs and toads), with no gills or tails, but possessing an amnion and cloaca. 

 These represent the parent forms of the three great higher branches of 

 vertebrates Reptilia, Aves (which evolved from reptiles), and Mammalia, 

 and are placed in the Permian period, in which have been found fossilised 

 amphibians and true reptiles. Monotremata (Promammalia) are the next 

 forms developed in our pedigree, the parent forms of the class Mam- 

 malia ; with cloaca, amnion, and marsupial bones ; which are placed in 

 the Triassic period ; and from which evolved Marsupialia, mammals with 

 amnion and marsupial bones, but no cloaca ; allied to the kangaroo and 

 opossum of to-day. This species we place in the Jurassic and Cretaceous 

 periods. From Marsupialia developed the large kingdom of Placentalia, 

 which lose the marsupial bones and cloaca, and acquire a placenta, and 

 which we divide into three main branches, according to the particular 

 placental formation. The first division we call Villiplacentalia (tufty 

 placenta), from which evolved Edentata (sloth, ant-eaters, and tertiary 

 monsters), Cetacea (marine placental mammals, such as whale, dolphin, 

 porpoise, and sea-cow), and Ungulata (horse, cow, pig, rhinoceros, and 

 hippopotamus). The second division we term Zenoplacentalia (ring-like 



