COMMON THYONE. 



287 



by the more frequent involutions and evolutions of its oral 

 end, evinced its uneasiness. Being left unobserved in this 

 state for an hour or so, I found on my return that it had 

 vomited up its tentacula, its oral apparatus, its intestinal 

 tube entire, and a large cluster of ovaries which lay about 

 the plate. The muscular convulsion must have been very 

 great that thus so completely embowelled the creature ; 

 and yet life was not extinct, for the tentacula contracted 

 themselves on being touched, and the empty skin appeared 

 by its motions to have lost little of its irritability." 



Dr. Johnston conjectures the water is conducted into 

 the body through the tubes, and then floating round the 

 respiratory filaments is ultimately forced through the canal 

 that leads to the anus. In all of the species I have 

 examined, I do not think this possible, the feet resembling 

 in their structure internally and externally those of the 

 Starfish and Sea- Urchin. In some works it is stated that 

 the Echinodermata fill their bodies with water by swallow- 

 ing it, but the statement is based on no foundation. On 

 cutting open a distended Oucumaria frondosa, Mr. Goodsir 

 and I found the water entirely lodged between the sides 

 and the external coats of the intestinal canal. How it 

 enters is a problem yet to be solved. 



