SEA SQUIRTS. 



243 



These are the branchial apertures of a colony of Ascidians 

 (Leptoclitium gelatinosum), and if we search around the mass 

 we shall shortly find a cone-shaped opening in the clear jelly, 

 through which a current of water flows. This is the common 

 atrial chamber of the whole colony. The clear jelly is the 

 common outer tunic of the whole community. 



On the walls of overhanging rocks, at low-water, many 

 fleshy clusters, like pale-coloured strawberries will be found, 

 of firm gelatinous material, with a clear jelly envelope, through 

 which the crimson dots of the contained squirts may be seen. 

 One form has a thick trunk, with but slightly enlarged head, 

 and consisting of a number of groups of squirts : this is Apli- 

 dium; it has no common aperture. A more globose head on 

 a shorter stalk has a distinctly marked common opening : this 

 is Polyclinum. Amaroecium has a corrugated exterior, and is 

 more cylindrical in form. 



BOTRYLLUS. 



Other species will meet us of more symmetrical form, on flat 

 weeds, smooth stones, and under the overhanging brows of 

 the large rocks at low-water. These are of varied tints accord- 

 ing to species, but each with a starry pattern worked in with 



