2l8 BY THE DEEP SEA. 



be flush with the general surface ; and its dorsal integument 

 was not only whitish with small darker marks which exactly 

 reproduced the appearance of the Leptoclinum surface with 

 the ascidiozooids scattered over it, but there were also two 

 larger elliptical clear marks which looked like the large com- 

 mon cloacal apertures of the Ascidian colony. I did not notice 

 the Lamellaria until I had accidentally partly dislodged it in 

 detaching the Leptoclinum from a stone. I then pointed it 

 out to a couple of naturalists who were with me, and we were 

 all much struck with the difficulty in detecting it when in situ 

 on the Ascidian. 



*' This is clearly a good case of protective colouring. Pre- 

 sumably the Lamellaria escapes the observation of 

 its enemies through being mistaken for a part of 

 the Leptoclinum colony ; and the Leptoclinum being 

 crowded like a sponge with minute sharp-pointed 

 spicules is, I suppose, avoided as inedible (if not 

 actually noxious through some peculiar smell or 

 taste) by carnivorous animals which might devour 

 such things as the soft unprotected mollusc. But 

 the presence of the spicules evidently does not 

 protect the Leptoclinum from Lamellaria, so that 

 we have, if the above interpretation is correct, the 

 curious result that the Lamellaria profits by a pro- 

 tective characteristic of the Leptoclinum for which it has itself 

 no respect, or to put it another way, the Leptoclinum is pro- 

 tected against enemies to some extent for the benefit of the 

 Lamellaria which preys upon its vitals." 



Since the publication of Prof. Herdman's note, I have 

 frequently found Lamellaria on the undersides of large stones 

 at low-water on the Cornish coast. I have always found it on 

 Leptoclinum gelatinosum, and can quite endorse his remark as 

 to the difficulty of distinguishing it. On one occasion I found 

 no less than four specimens feeding upon one patch of the 

 ascidians, and pointed them out to a friend, who, however, 



