46 THE AGGREGATE TUNICATA. 



bunch consisting of ten or twelve individuals diverging 

 from a common centre. The figure of each distinct 

 being is oval, with an imbibing orifice at the apex, the 

 excretory orifice opening into a common central cavity. 

 Cuvier observes, that if the imbibing or external orifice 

 of one of these beings be irritated, the animal to which 

 it belongs only contracts ; but that if the centre to 

 which they converge be irritated, they all shrink in 

 unison. 



Still more curious and wonderful is the jyj/ro5owa, 

 one of the luminous tenants of the ocean, of which an 

 account will be given in the next chapter. 



The aggregate tunicata, constituting the group termed 

 polyclinimn, closely resemble in individual structure the 

 ascidioe, but are collected into conglomerate masses of 

 a conical or globular form, or they are grouped so as 

 to resemble expanded flowers. These are attached to 

 rocks and stones, which they ornament with a living 

 tuft ; the external orifice of each individual is sur- 

 rounded with a little star, composed of six rays ; and 

 the viscera of each are prolonged into the common 

 gelatinous mass. 



So far have we endeavoured to give an idea of the 

 structure of the tunicate mollusca ; and who can con- 

 template life under the organic forms they assume — who 



