18 INVEBTEBRATE ANIMALS. 



Group 52.— Class TUNICATA. Tunica, a cloak. The 

 Ascidians, or Tunicaries, are marine animals, having 

 their internal organs protected by a double integu- 

 ment, tough and elastic, in place of a shell. Estimated 

 number of species : recent, 150; British, 73. 



H Coloured drawings of solitary, social, and com- 

 pound Ascidians. 



upper Compartment. 



Preparations in spirits of Salpians in the chained 

 and solitary states ; also of Pyrosoma, and 

 many other Ascidians. Diagrams of the early 

 development of an Ascidian, shewing by the 

 presence of a pseudo-notochord its approach 

 to the form of the vertebrate embryo. 



Group 53.— Class BRACHIOPODA. /3p«;^;«;v, the arm ; 

 TTovs, a foot. The Lamp-shells possess a true upper and 

 under valve. Estimated number of species : recent, 

 100 ; British, 5 ; fossil, 1,000, from the Silurian 

 upwards, 



II Examples of nearly all the recent, and of a few 

 of the fossil genera. 



Upper Compartment. 



Animals of Lingula, and other Brachiopoda in 

 spirits. ^ 



Group 54.— Order RUDISTES (Lamarck). Estimated 



number of species : recent, none known at present ; 



fossil, 100, from the Chalk and Hippurite Limestone. 



H Examples of Hippurites ; Specimens of Radiol- 



ites, Caprinella, Caprina, and Caprotina, are 



desiderata. 



