Family Dasyproctidae. Coelogenys—paca.
Dasyprocta—agouti.
Family Caviidae. Cavia—guinea-pig.
Hydrochaerus—capybara.
Suborder (2). Duplicidentata.
Family Leporidae. Lepus—hare and rabbit.
Order 6. Carnivora.
Suborder (1). Creodonta.
Family Hyaenodontidae. Hyaenodon.
Suborder (2). Carnivora vera or Fissipedia.
Section Æluroidea.
Family Felidae. Felis—cat, lion, tiger.
Machaerodus—sabre-toothed lion.
Family Viverridae. Viverra—civet.
Paradoxurus—palm civet.
Family Protelidae. Proteles—aard wolf.
Family Hyaenidae. Hyaena.
Section Cynoidea.
Family Canidae. Canis—dog, wolf, fox.
Section Arctoidea.
Family Ursidae. Ursus—bear.
Family Mustelidae. Latax—sea otter.
Suborder (3). Pinnipedia.
Family Otariidae. Otaria—sea lion.
Family Trichechidae. Trichechus—walrus.
Family Phocidae. Ogmorhinus—sea leopard.
Order 7. Insectivora.
Suborder (1). Dermoptera.
Family Galeopithecidae. Galeopithecus—'flying lemur'.
Suborder (2). Insectivora vera.
Family Macroscelidae. Macroscelides—jumping shrew.
Family Erinaceidae. Erinaceus—hedgehog.
Gymnura.
Family Soricidae. Sorex—shrew.
Family Talpidae. Talpa—mole.
Family Potamogalidae. Potamogale.
Family Solenodontidae. Solenodon.
Family Centetidae. Microgale.
Centetes—tenrec.
Family Chrysochloridae. Chrysochloris—golden mole.
Order 8. Chiroptera.
Suborder (1). Megachiroptera.
Family Pteropidae. Pteropus—flying fox.
Suborder (2). Microchiroptera.
Family Rhinolophidae. Horseshoe bats.
Family Phyllostomatidae. Desmodus—vampire.
Order 9. Primates.
Suborder (1). Lemuroidea.
Family Tarsiidae. Tarsius—tarsier.
Family Chiromyidae. Chiromys—aye aye.
Suborder (2). Anthropoidea.
Family Hapalidae. Hapale—marmoset.
Family Cebidae. Mycetes—howling monkey.
Ateles—spider monkey.
Family Cercopithecidae. Cynocephalus—baboon.
Macacus.
Colobus.
Family Simiidae. Hylobates—gibbon.
Simia—orang.
Gorilla.
Anthropopithecus—chimpanzee.
Family Hominidae. Homo—man.
CHAPTER III.
SKELETON OF HEMICHORDATA, UROCHORDATA, AND CEPHALOCHORDATA.
SUBPHYLUM A. HEMICHORDATA.
The subphylum includes three genera, Balanoglossus[19], Cephalodiscus and Rhabdopleura; and perhaps a fourth, Phoronis.
The skeletal structures found in Balanoglossus[20] are all endoskeletal. They include:
(1) The notochord. This arises as a diverticulum from the alimentary canal which grows forwards into the proboscis and extends beyond the front end of the central nervous system. It is hypoblastic in origin and arises in the same way as does the notochord of Amphioxus. Its cells become highly vacuolated and take on the typical notochordal structure[21]. The cavity of the primitive diverticulum becomes obliterated in front, but behind it opens throughout life into the alimentary canal.
(2) The axial skeletal rods. These are a pair of chitinous rods which lie ventral to the notochord and in the collar region unite to form a single mass.
(3) The branchial skeleton. The gill bars separating the gill slits from one another are strengthened by chitinous rods in a way closely similar to that in Amphioxus. But between one primary forked rod and the next there are two secondary unforked rods—not one, as in Amphioxus.
(4) The chondroid tissue. This is of mesoblastic origin and may be regarded as an imperfect sheath for the notochord.
In Cephalodiscus and Rhabdopleura as in Balanoglossus the notochord forms a small diverticulum growing forwards from the alimentary canal into the proboscis stalk.
Recent researches on Phoronis[22] show the existence in the collar region of the larva (Actinotrocha) of a paired organ, which is regarded by its discoverer as representing a double notochord.
SUBPHYLUM B. UROCHORDATA (Tunicata).
Skeletal structures of epiblastic and hypoblastic origin occur in the Urochordata. Most Tunicates are invested by a thick gelatinous test which often contains calcareous spicules, and serves as a supporting organ for the soft body. The cells of this test are mesodermal in origin.
In larval Tunicata and in adults of the group Larvacea the tail is supported by a typical notochord, which is confined to the tail. In all Tunicata except Larvacea all trace of the notochord is lost in the adult.
SUBPHYLUM C. CEPHALOCHORDATA.
| 1. skeleton of dorsal fin. | 5. branchial skeleton. |
| 2. notochord. | 6. septa separating the |
| 3. neural tube. | myotomes. |
| 4. buccal skeleton. | 7. skeleton of ventral fin. |
This