134 ANATOMY AND LIFE HISTORY OF MOLLUSCA. 



too readily to forego searching for a purpose in insignificant 

 details. Though this may appear to many a very antiquated 

 idea, in practice it encourages one to attempt the solution of many 

 an interesting problem. 



I shared the interest and wonder of the public at the discovery 

 made by the great naturalist of the Challenger, and I immediately 

 recurred to the old observations made on Australian shells, 

 particularly Patella, Anatina, Lima, Trigonia, and the littoral 

 shells generally. No time was lost in making investigations, 

 though no success was expected with Patella, as Mr. Mosely had 

 looked in vain for the small eyes amongst some species of this genus. 

 With some shells, I was not successful, and, as often is the case, 

 these being the first tried led to discouragement and almost an 

 abandonment of the search. But remembering the more conspicuous 

 instances amongst the genera above mentioned, I renewed the 

 investigation, and was rewarded with the discovery of organs, 

 which I have no doubt whatever, are similar to those described by 

 Prof. Mosely. I am fully aware, however, that what might satisfy 

 me in a matter of the kind will require something more to meet 

 all the objections which may be felt by other observers, and 

 therefore beg to record the discovery, if such it be, with some little 

 diffidence, knowing the deficiencies under which I laboured for 

 want of technical apparatus, and also of experience in the higher 

 paths of microscopical examinations, However, I shall give the 

 public the fullest opportunity of verifying or disproving my 

 conclusions by every detail about my methods and the supposed 

 facts observed. It is to be hoped after this there will not be much 

 error involved. In any case, I feel confident that as the examples 

 quoted are of easy access, my conclusions will be speedily confirmed 

 or otherwise. 



Briefly, therefore, I may now state that I have found on a 

 large number of shells, eyes of the kind described by Prof. Mosely ; 

 that is, associated with sense-organs and supplied with nerve 

 channels of a similar kind. These eyes have been observed in 

 various forms, on so large a proportionate number of shells, that 

 I am inclined to regard their absence as rather the exception, 

 but as in matters of detail there is considerable difference in 

 the mode in which the eyes occur, their number and position, 

 it is necessary to arrange a classified list of these organs. 



Eyes and sense-organs in the Mollusca may be divided into four 

 kinds, that is : — 1 Minute organs in great numbers on the outer 

 surface or tegmentum of the shell of both bivalves and univalves. 

 2. Large and solitary eyes in the shell-substance or on the horny 

 tissues, in size and in special peculiarities to be afterwards 

 described, like the tentacular eyes. 3. Eyes on the mantle-lobes 

 of both bivalves and univalves, generally on stalked pedicels, but 



