420 Mr. E. A. Smith on Haliotis. 



which subsequently is formed into a complete raised per- 

 foration. The number of perforations which remain open 

 indicates the extent of the mantle-slit, but not the number of 

 the tentacular filaments along the margins. 



In this example four of the holes of the outer or normal 

 series are open, whilst of the inner series, which runs 

 parallel with the other at a distance at the widest part of a 

 little more than an inch, all are closed or filled up. From 

 this I conjecture that the edge of the mantle at this particular 

 point was accidentally notched in early life (or perhaps it may 

 have been a peculiarity from birth) and that the notch was 

 not deep. 



The perforations in the shells of this genus are supposed to 

 be for conveying water to the branchiee and also, to some 

 extent, for the extrusion of faical matter. This theory in all 

 probability is correct, as the gills and anal opening are situated 

 immediately beneath, and one fails to see what other purpose 

 they can serve. There being neither gills nor anal opening 

 under the abnormal series of holes, they had no special func- 

 tion to perform, and consequently the animal appears to have 

 filled them up with nacre from within as soon as possible, so 

 that not even the last-completed one is left unclosed. 



The supposed abnormal slit or peculiarity/ in the mantle 

 must have been present when the creature was very young, 

 for the series of holes is noticeable to within an inch of the 

 apex, where the shell is so eroded that traces of both this and 

 the outer series become obliterated. The growth of this 

 abnormal series seems to have been more slowly effected than 

 that of the outer row, since, in the same period, which can be 

 judged of by the lines of growth, twelve were produced in the 

 latter to eight in the former. 



In the figures of the European Haliotis tuhercalata which 

 appear in the works of Cuvier * and Fischer f it will be 

 observed that a tentacle is protruded through each of the last 

 six or seven perforations. Cuvier, however, only describes 

 " trois ou quatre filets " on the edges of the mantle-slit, and 

 therefore it is all the more remarkable that in the figure 

 referred to seven are represented. In another figure on the 

 same plate (figure 11) three only are shown (the actual 

 number which exists), and these are drawn in the relative 

 positions which they seem invariably to occupy. 



I have carefully examined three specimens of H. tuhercu- 

 lata and examples of five other species from various parts of 



* Anat. MoUusques, pi. i. fig. 9. 



t Man. Conchyl. fig. 696 (from an unpublished cut by Deshayes). 



