on the Natural Group of Tnmcatai^f .\i 531 



Hv^cu^}}), and communicating with a fleshy intestine {to ara,^x,uhg) ; 

 so that the intestine of the Tethijoji appears contained in this 

 reticulated membrane. Although, indeed, the flesh is alike in 

 all testaceous animals, this intestine resembles in form that of 

 none of them. It is suspended at two places, viz. to the above- 

 mentioned membrane, and to the muscle* which proceeds from 

 the side ; and wherever it adheres to either of these it is narrowest. 

 At each point of suspension this intestine tends towards those 

 orifices which lead to the outside of the test, and by which it re- 

 ceives and discharges its food and water ; so that if one of these 

 apertures be the animal's mouth, the other must be its anus. One 

 of these orificial processes is thickert than the other. Within 

 the cavity also of one or other of them there is a certain small 

 cohering substance which divides it." 



These preliminary remarks, and particularly this accurate 

 though ancient description of an Ascidia, will be sufficient to 

 enable any person to pursue the tenour of the following de- 

 scriptions : but in order to understand them thoroughly, I need 

 scarcely say that a perusal of the admirable memoirs of Cuvier 

 and Savigny is indispensable. 



The Tunicata:|., then, are animals which connect the Acrita 

 or lowest primary division of the animal kingdom with the Mol- 

 lusca. From the Mollusca, however, they differ in having an exter- 

 nal covering consisting of an envelope distinctly organized and 

 provided with two apertures, of which one is branchial, the other 

 anal. They also differ from the Mollusca as well in their mantle 



* Literally it is " to the skin from the side ;" and in fact the suspending muscle is 

 exceedingly like a piece of the tunic. 



■f- This is the branchial orifice; and I suspect that the small cohering or continuous 

 substance which Aristotle alludes to immediately afterwards, is the valvule of the anal 

 orifice. 



;j: According to his usual practice of changing names, — a practice which interferes 

 so much with his well-merited reputation, — M. de Blainville calls this group Hetero- 

 branchiata, a name without one single quality to recommend it. 



VOL. XIV. 3 z forming 



