POSTSCRIPT. 
“ Nulla dies sine linea,” was the recommendation of him 
who brought into systematical arrangement the mighty ma¬ 
terials of created nature : and long experience has taught 
us, “ that each day is the disciple of that which has gone 
before.” 
In looking carefully over some fine specimens of the 
Serpula tubularia, among which various other species were 
entwined, we observed several of our Patella tricornis, and 
P. Extinctorium attached to them, some of which closed up 
the orifices of the tubes. This circumstance has led us to 
the supposition that they may eventually turn out to be the 
opercula or lids of different SerpuUe. But as the animal 
inhabitants of such as we examined were dead and shrunk 
deep into the tubes, we could perceive no kind of attach¬ 
ment. Anxious a 3 we are to ascertain whether these are 
actually specific productions, or merely the lids of other 
shells, we can at present only issue our suspicions on the 
subject, not being able immediately to refer to fresh and. 
living specimens of these Serpuke : and as our last proof 
sheet is now before us for revision, we must in a few’ hours 
close all further communication through this channel. 
By the few conchological friends around us they have 
been considered as Pat ell m : and it maybe remarked, that 
no author, as far as we know, has taken any notice of such 
opercula ; not even Montagu, who has given much atten¬ 
tion to the formation of the animals of this tribe. 
If therefore we are in error, it is an error which perhaps 
better naturalists than ourselves might casually have fallen 
into: and we are solicitous to point out the easy means by 
which these singular productions may be arranged in their 
proper place. ^ 
r 1 L z 2 Cardium 
