ANIMAL REPRODUCTIONS. 279 
black point, which included the horns joined 
“in one. In other five, that repaired the head 
© completely, were two black points on the fides 
© of the tubercle, and a black line was afterwards 
* obferved connected with them. Thefe points 
* were manifeftly the eyes and the lines, the op- 
© tic nerves. One of the heads was not repaired 
* in lefs than four months and a half. The re- 
* production was undoubted, becaufe all four, 
* which are ftill alive, fed on young lettuce, and 
© alfo drew the operculum within the fhell. 
* There is no wonder that nature has provided 
* a protection fuch as the cover ; for decapitated 
‘{nails, from long abftinence, want that cluten 
* with which their lofs is repaired ; and it is af- 
‘ ways thinner, according te the duration of ab- 
* f{tinence. 
‘ The reparatory matter of the operculum fails 
* in different periods of time. ‘Some {nails ceafe 
< to repair itin nineteen days, others in forty- 
‘eight. The defe& of gluten alarmed me for 
‘ the fafety of my four remaining {nails, there- 
* fore I kept them in a warm fituation; and they 
* repaired a very thin operculum, which was 
* proof they had fed. 
‘ The reparation of the fmal! horns is always 
© more tardy, compared to the large ones and the 
« lips; neither are the horns always of the fame 
s length and thicknefs, I have never feen the 
: S 4 } € fhagreen 
