THE EYES. 305 



accepting or rejecting. Probably it is in the exercise 

 of the latter discretion that those irregular regurgita- 

 tions of the current take place, accompanied by a 

 momentary closing of the mouth, that we frequently 

 notice. 



Still further ancillary to the protection of the stomach 

 from the intrusion of inimical matters, we may safely 

 suppose certain eye- like specks which are placed at the 

 very vestibule. In the larger species, as this red- 

 clouded green Squirter, there are seated in special 

 fissures at the very margin of the expanded siphon- 

 orifices, red dots, eight around the receiving, six 

 around the ejecting, siphon. Each dot seems ascer- 

 tained to be an eye of very rudimentary structure, 

 seated on a mass of orange pigment. We should pro- 

 bably do wrong if we attributed any higher vision to 

 these organs than a low degree of sensibility to the 

 general stimulus of the light. 



Some species have the orifices of the siphons four- 

 cornered, whereas the sort I have been describing have 

 them circular ; there are differences also in the breath- 

 ing sac, which in the square -mouthed species is folded 

 lengthwise, while in the round-mouthed it is plain. 

 Hence the former have been separated from the Ascidice, 

 as a distinct genus, named Cynthia ; both including a 

 large number of species. 



