106 THE NAUTILUS. 



of substances represents the only repugnatorial material pos- 

 sessed by Chromodoris. It seems possible that the oily element 

 of the secretion is particularly involved in the production of the 

 curiously penetrating odor which the nudibranch emits, and 

 that some other substance is also concerned in determining the 

 general distasteful quality. 



Incidentally, the glands cannot be implicated in any mutual 

 attraction between individuals at the time of pairing, for ani- 

 mals from which the glandular equipment has been completely 

 removed, are found to mate readily and deposit normal egg 

 masses. 



I have commented above on the suggestive appearance of pro- 

 tection evidenced by the inturning of the posterior beaded border 

 of the mantle. A closer analysis shows, however, that any pro- 

 tection which is in this way afforded to the conical glands is 

 purely incidental. For if the projecting "tail" of the nudi- 

 branch is stimulated (as with induction shocks), the beaded 

 portion of the mantle is not rolled under upon itself, but is 

 spread out so that the openings of the glands point in the gen- 

 eral direction of the irritated area. Their discharge under these 

 circumstances may occasionally be seen. I therefore believe 

 that the ventralward inflection of the gland-bearing portion of 

 the mantle is primarily a reaction having to do with the normal 

 discharge of the glands. When the nudibranch is attacked at 

 the side, or anteriorly, the glands are thus given an opportunity 

 to discharge a part of their contents in an appropriate direction. 



A full account of these observations wili be published later. 



Agar's Island, Bermuda. 



THE ANATOMY OF CONTRADENS CAMBOJENSIS (SOW.) (NAYADES). 



BY DR. A. E. ORTMANN. 



Two specimens, male and gravid female, from Petchaburi, 

 Siam, are at hand, received from B. H. Bailey, and collected 

 by Dr. E. B. McDaniel. 



These specimens agree very well with Unio cambojensis Sow- 

 erby (Conch. Icon. 18. Unio. 1866, pi. 42, f. 231), in general 



