THE POLYZOA 119 



bratula, Rhynchonella). Sometimes, however, the 

 pedicle passes out between the valves (Lingula^ 

 e.g.), in which case there is no foramen ; or it 

 may be arranged in other ways. Sometimes the 

 shell is merely attached to the ground by its 

 side, like an oyster. Some forms are enormously 

 widened in a lateral direction, e.g. Spirifera, and 

 the Productus above named. Lingula, among 

 others, is remarkable as being a form that has 

 survived from the earliest geological period to 

 the present day. 



The larva, in its best known forms, passes 

 through the typical larval stages of the animal 

 kingdom. It is first a one-layered larva, then a 

 two-layered form, and then becomes a ciliated 

 animal. In this three regions may be distin- 

 guished, representing respectively the head, body, 

 and pedicle. 



The shells of the Brachiopoda, including the 

 kinds above named, may be seen by the reader 

 in any geological museum. 



CHAPTER XI 



THE POLYZOA ; MOSS-CORALS AND SEA-MATS 



WE have already described the creatures which 

 are popularly known as Corallines. Modern zo- 

 ologists have long separated off from the Coral- 

 lines of the older writers, a group of animals 

 known as the Sea-Mats, which also are colonies 

 made up of unit individuals. The common Sea- 

 Mat, Flustra foliacea, may be picked up on al- 

 most any part of the English coast, being often 



