CIONA FASCICULARIS. 17 



yellow, or nearly colourless. The longitudinal muscular 

 hands are extremely delicate, so much so that it is 

 difficult to trace them ; they extend, however, into the 

 tubes and reach to the bottom of the pallia! sac, where 

 the fibres are a little diffused. 



The branchial sac (PI. XXII, fig. 5) is extremely 

 elongated and nearly cylindrical ; the primary vessels 

 are very regularly disposed, the larger ones having 

 three or four smaller between them. The oral filaments 

 are long, slender above, and widened a little at the base; 

 they correspond in number to the large primary vessels. 

 The branchial tubercle is small and transversely oval. 

 The tentacular filaments (PI. XXII, fig. 8, and fig. 29 in 

 text) are arranged on a narrow undulated fold or collar ; 

 they are long and slender with intermediate short ones ; 

 in all about seventy. They are quite colourless. 



The alimentary tube is disposed much in the same 

 manner as it is in C. intestinalis, only it is more de- 

 cidedly pendant, as it were, from the branchial sac ; 

 and the stomach, instead of being placed across the 

 visceral chamber, hangs downwards ; the oesophagus, 

 which is rather long and narrow, enters it above, and 

 the intestine leaves it below ; it is well marked and is 

 pretty-regularly oval. The intestine sinks to the 

 bottom of the mantle, and then, turning upwards and 

 backwards, forms a short open loop ; it crosses over 

 on the right side of the stomach in a sigmoidal curve, 

 and on reaching the ventral margin passes up by the 

 side of the branchial *sac to the lower end of the 

 atrium, terminating about one third up the body. The 

 margin of the anal opening is lobed and reflected. 



The ovary is placed in the intestinal loop on the 

 right of the stomach ; it is an elongated, somewhat 

 clavate mass, with the oviduct passing from the 

 attenuated extremity. The genital outlets are placed 

 high up in the atrium, not much below the atrial tube 

 and considerably in advance of the anal orifice ; two 

 canals end in a compound nipple with a double outlet, 

 or rather, in two minute nipples placed side by side. 



TI. 2 



