xni PHYLUM CHORDATA 23 



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

 three genera, Doliolum, Anchinia, and Dolchinia. 



Sub-Order &. 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. 



Sub-Order c. Pyrosomata. 



Thaliacea 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 sub-order comprises only one family the Pyrosomidce, with 

 one genus, Pyrosoma. 



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 

 considerable 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 peribrarichial cavity, which communicates 

 with the exterior by an atrial aperture. Many form colonies by 

 a process of budding ; and most undergo a metamorphosis, the larva 

 being provided with a caudal appendage, supported by a notochord 

 similar to that of the Larvacea. 



Suit-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 1. Ascidice composite. 



Fixed Ascidians which form colonies of zooids, embedded in a 

 common gelatinous material without separate tests. 



This order includes Botryllus, Amarcecium, Diazona, and a 

 number of other genera. 



