242 THE STUDY OF ANIMAL LIFE CHAP. 



Britain and elsewhere. The voracious Aulostoma is 

 rather carnivorous than parasitic. The land-leeches (e.g. 

 Hcemadipsa ceylonica), though small and thin, are very 

 troublesome, sucking the blood of man and beast. Among 

 the others are the eight-eyed Nephelis of our ponds, the 

 little Clepsine which sometimes is found with its young 

 attached to it, the warty marine Pontobdella which fastens 

 on rays, Piscicola on perch and carp, Branchellion with 

 eleven pairs of respiratory leaflets of skin, and the largest 

 leech the South American Macrobdella valdiviana, 

 which is said to attain a length of over two feet. 



Possibly related to the Annelid series are two other 

 classes 



Class Chaetognatha, including two genera of small 

 arrow-like marine " worms," Sagitta and Spadella. 



Class Rotifera, " wheel animalcules," abundant and 

 exquisitely beautiful animals inhabiting fresh and 

 salt water and damp moss. The head-region bears 

 a ciliated structure, whose activity produces the 

 impression of a swiftly rotating wheel. Many of 

 them seem to be entirely parthenogenetic. Some 

 can survive being made as dry as dust. 



But there are yet other classes included in this difficult 

 assemblage of ' worms ' 



Class Sipunculoidea, ' spoon-worms ' ' living in the 

 sea, freely or in tubes, e.g. Sipunculus. 



Class Priapulidea, including several marine worms. 



Class Phoronoidea, including Phoronis and Phoro- 

 nopsis. 



Class Polyzoa or Bryozoa, with one exception 

 forming colonies by budding, in fresh water or in 

 the sea, e.g. the common sea-mats or horn-wracks 

 (Flustra). 



Class Brachiopoda or Lamp-shells, a class of marine 

 shelled animals once much richer in members, now 

 decadent. They have a superficial, but only a 

 superficial, resemblance to Molluscs. 



We have not catalogued all these classes of " worms ' 



