DEFINITION OF AN LACE. 9 



Vertebrata 



Anamniota (Anallantoidea) 

 Ichthyopsida 

 Pisces 



Marsipobranchia (lampreys, etc.) 

 Ganoidea (sturgeon, etc.) 

 Teleostea (bony fishes) 

 Elasmobranchia (sharks, skates, etc.) 

 Dipnoi (lung-fishes) 

 Amphibia 



Urodela (newts, salamanders, et:.) 

 Ansura (frogs, toads) 

 Amniota (Allantoidea) 

 Sauropsida 



Reptilia (lizards, crocodiles, snakes, turtles, etc.) 

 Aves 

 Mammalia 



Montotremata (duck-bill, etc.) 

 Marsupialia (opossum, kangaroo, etc.) 

 Placentalia 



Unguiculate series 



Insectivora (moles, etc.) 

 Cheiroptera (bats) 



Rodentia (rats, rabbits, guinea-pigs, etc.) 

 Carnivora (cats, dogs, etc.) 

 Primata (lemurs, monkeys, apes, man) 

 Ungulate series 

 Ungulata 



Artiodactyla (even-toed) (cattle, sheep, pig, deer, etc.) 

 Perissodactyla (uneven-toed) (horse, rhinoceros, etc.) 



Of the invertebrate animals there will be little to be said. There are two 

 types of invertebrates which show relationship in their structure to true verte- 

 brates. One of these is the class of jointed worms, or Annelids; the other is the 

 class of Atriozoa, which comprises the subdivisions of Tunicata and of the Cepha- 

 lochorda. All of our observations on the development of this last type are based 

 on the one genus, Amphioxus, which will therefore be the name which, we shall 

 use whenever we have to refer to these animals. 



Definition of Anlage. 



There will be frequent occasion to use this word in a strictly technical sense. 

 It has been adopted from the German, as there is no satisfactory English equiva- 

 lent for it. The French use the word "ebauche" and the Italians " abozzo." 

 Primordium has been proposed as the Latin equivalent and is used by a few 

 American authors, but anlage is generally employed by both American and English 

 writers. "Anlage'' may be denned as follows: The first accumulation of cells 

 in the developing embryo recognizable as the commencement of a structure, organ, 

 or part. 



