80 ARTHROrODA. 



Order IV. PHYLLOPODA. 

 BRAXCIIIOPODA. ASPIDOPHORA. CERATOPHTHALMA. 



Body divided into many segments, nearly all carrying a pair of 

 loliaceous legs. Antennae small, one or two pairs, not natatory. 



The legs vary from eleven to sixty pairs. The abdomen is 

 many -jointed, terminating in two long setaceous appendages. The 

 eyes are two, or sometimes three ; occasionally, as in Branchipua, 

 they are pedunculate. Branchipodidce have no carapace ; they 

 swim on their backs. Apodidie have a large shield-shaped 

 carapace. In Estheriidse the body is enclosed in a soft bivalve 

 shell. 



Apus cancriformis, two or three inches long, sometimes met 

 with in this country, changes its skin twenty times in two or 

 three months. The males were unknown a few years ago. The 

 name UTTOVS, given by Frisch in 1732, and adopted by later 

 authors, is unwarranted. The family name is Apusidae for Claus. 



The sudden appearance of animals of this order is due to the 

 latent vitality of their ova, which are only hatched under favour- 

 able conditions. They are mostly freshwater animals. 



Apodidce. Branchipodida. Esther iiclce. 



Apus. Artemia. Limnadia. 



Lepidurus. Branchipus = Chirocephalus. Estheria. 



Order V. TEILOBITA. 

 PAL.EAD.E. 



Marine animals, often of large size, belonging to the Palamoie 

 period. Cephalic shield with two sutures dividing the median 

 from the two lateral regions. Limbs rudimentary, lamelliform. 



These extinct Crustaceans are believed to be allied to Apus and 

 Nebalia. Their body is composed of from six to twenty segments, 

 and the tail or postabdomen is bent under the thorax. The 

 limbs are unknown. According to Schmarda, there are 1600 

 species ; he enumerates seven families. They have been found 

 almost entirely in the Palaeozoic rocks. Among the principal 

 genera are : 



*Isoteles. *Asaphus. *0gygia. 



*Amphyx. *Calymene. *Paradoxides. 



*A.rges. *Homalonotus. *Trinucleus. 



