22 ZOOLOGY SECT. 



This sub-order contains only one family, the Doliolidce, with the 

 three genera, Doliolum, Anchinia, and Dolchinia. 



Sub-Order b. Hemimyaria. 



Thaliacea with a more or less fusiform body, with sub-terminal 

 oral and atrial apertures. The muscular fibres are arranged in 

 bands which do not form complete rings. There is no tailed larval 

 stage. 



This sub-order is probably best looked upon as comprising only 

 one family, the Salpidce. 



ORDER 3. ASCIDIACEA. 



Mostly fixed Tunicata, either simple or forming colonies by a 

 process of budding, and, in the adult condition, never provided 

 with a tail. The test is a permanent structure, usually of con- 

 siderable thickness. The muscular fibres of the mantle (body- 

 wall) are not arranged in annular bands. The pharynx is large, 

 and its walls are perforated by numerous stigmata leading into a 

 surrounding atrium or peribranchial cavity, which communicates 

 with the exterior by an atrial aperture. Most undergo a meta- 

 morphosis, the larva being provided with a caudal appendage, 

 supported by a notochord similar to that of the Larvacea. 



Sub-Order a. Ascidice simplices. 



Ascidians in which, when colonies are formed, the zooids are not 

 embedded in a common gelatinous mass, but possess distinct tests 

 of their own. They are nearly always permanently fixed and 

 never free-swimming. 



Including all the larger Ascidians or Sea-Squirts. 



Sub-Order b. Ascidice composite. 



Fixed Ascidians which form colonies of zooids, embedded in a 

 common gelatinous material without separate tests. 



This order includes Botryllus, AmarcBcium, Diazona, and a 

 number of other genera. 



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ORDER 4. LUCIDA. 



Pelagic Tunicata which reproduce by budding, so as to give 

 rise to hollow cylindrical colonies, open at one or both ends, having 

 the zooids embedded in the gelatinous wall in such a manner that 

 the oral apertures open on the outer, the atrial on the inner surface 

 of the cylinder. There is no tailed larval stage. 



This order comprises only one family, the Pyrosomidcs, with one 

 genus, Pyrosoma. 



