184 INVERTEBRATE ZOOLOGY 



Class III. Trochelminthes (Rotifera). Minute aquatic trochozo- 

 ans with mouth surrounded by a band of cilia. Ex. Rotifer. 



Class IV. Bryozoa (Polyzoa). Trochozoans with ridge of ciliated 

 tentacles around the mouth ; usually sessile and colonial. 



Order 1. ENDOPROCTA. Bryozoans with the anus within the 

 crown of tentacles. Ex. Pedicellina. 



Order 2. ECTOPROCTA. Bryozoans with the anus without 

 the crown of the tentacles. Ex. Bugula. 



Class V. Brachiopoda. Sessile trochozoans with a dorsal and a 

 ventral bivalve shell. Ex. Lingula. 



Class VI. Nemertini. Flat, elongated, free-swimming worms 

 with ciliated bodies ; a protrusile proboscis present above mouth. 

 Ex. Cerebratulus. 



Subtype II. ARTICULATA. Trochozoans, the body of which con- 

 sists of a distinct head and an elongated, segmented trunk. 



Class I. Annelida. Elongated worms with equivalent segments 

 and without segmented appendages. 



Order 1. CHAETOPODA. Annelids with bristles (setse) seg- 

 mentally arranged. 



Suborder 1. Polychaeta. Chaetopods with appendages (para- 

 podia) on which are numerous bristles (setae). Ex. Nereis. 



Suborder 2. Oligochaeta. Chaetopods without appendages and 

 with few setse. Ex. Lumbricus. 



Order 2. HIRUDINEA. Annelids with a sucker at each end 

 and no bristles. Ex. Clepsine. 



Order 3. GEPHYREA. Annelids without body-segmentation 

 in the adult. Ex. Phascolosoma. 



Class II. Arthropoda. Articulates with segmented appendages. 



Subclass I. Crustacea. Aquatic and gill-bearing arthropods ; 

 two pairs of antennae present. 



Division I. ENTOMOSTRACA. Small, simply constructed crus- 

 taceans with a variable number of body-segments and without 

 abdominal appendages. 



Order 1. PHYLLOPODA. Entomostracans with flat, leaf -like 

 appendages. 



Suborder 1. Branchiopoda. Elongated phyllopods with seg- 

 mented body. Ex. Branchipus. 



