ZOOLOGY SECT. 



Distribution. The various species of Peripatus are all terres- 

 trial, and are found in damp localities, under bark, or dead timber, 

 or stones. Four species occur in South Africa, one in South 

 America and one of the West Indies, one in New Zealand, and 

 two in Australia. 



Relationships. Peripatus is the most primitive of existing 

 Arthropods, and presents some striking points of resemblance to the 

 Chsetopoda. The development is in the main arthropodan, 

 especially as regards the mode of segmentation (at least in the 

 forms with much food-yolk, which are probably the more primi- 

 tive), t,hc> mode of closure of tire blastopore, and the mode of 

 development of the mesodermal strands. Arthropodan also are 

 the relatively large size of the brain and the presence of tracheae, 

 the character of the heart with its pairs of ostia, together with 

 the clawed appendages, and the jaws in the form of modified 

 limbs. The nephridia on the other hand, and their modification 

 in certain segments to form the gonoducts, which are ciliated 

 internally, are annulate in character, and in all probability the 

 slime glands and coxal glands correspond to the setigerous glands 

 of the Cha?topoda. The nervous system is peculiar, and is most 

 nearly paralleled among the Platyhelminthes and the Mollusca. 

 Also peculiar, and serving to distinguish Peripatus from the rest 

 of the Arthropoda, are the large number of stigmata with their 

 irregular arrangement, the presence of only a single pair of jaws, 

 and the nature of the cuticle. 



CLASS III.- MYRIAPODA 



The class Myriapoda, including the Centipedes and the Milli- 

 pedes, consists of tracheate Arthropoda, which bear many features 

 of resemblance to the Insects. There is a distinct head, bearing 

 many-jointed antenna?, a pair of eyes, and two or three pairs of 

 jaws ; and a body, not distinguishable into regions, but consisting 

 of a number of similar segments, each bearing either one pair of 

 legs or two. A system of air-tubes or trachea, similar to those of 

 Peripatus and the Insects, open by a series of stigmata, usually in 

 considerable numbers, on the sides or lower surfaces of the 

 segments. 



A -DisTixiTivE CHARACTERS AND CLASSIFICATION. 



The Myriapoda are tracheate Arthropoda in which there is a 

 head, bearing antenna- and jaws, and a trunk made up of a number 

 of sjinil;, r segments, provided, except the last, with leg-like 

 appendages. Groups of ocelli take the place of the compound 

 eyes of Insects. 



