The in fide of the iliell is cloathed with a moveable membrane, finely ramified ^ 
purple and various-coloured veins, which terminate at the margin of it in a feries 
fibres, ee, feverally animated ; thefe are a fet of retra&ile polype-like organs, n ^ 
in various modes are ever waving about in the water, probably alfo inhaling noun ^ 
ment ; and may be the inftruments employed in making the continually neceffary a 
ditions to its fhell. 
The filament which generally covers the infide of the fhell, it can retraft and ^ 
pand at pleafure ; and at a little diftance from the edge, a curioufly-wrought 
.tine runs round it like net-work, each feveral part of which is often in motion, lik^ 
play of lungs. 
While the Limpet was under confi deration, there appeared feveral minute, unC °^, a 
mon living creatures darting about in the water, of a femi-tranfparent fubftance i ^ 
of thefe, which were got confined, fo as to be examined by the microfcope, are 
on the plate at G g, and F f, (the fmall letters indicating their natural fize) : ,unkn° 
to what tribes they belong. 
i of th® 
They were occafionally caught by the rapid movements of the tentacula ° ^ 
Accom or Barnacle , H h, and iuhamly fwallowed by ii, — fome proof that its blin 
tivity is not exerted in vain. 
This genus is called by Lanrueus, Lepas. The fpecimen here produced at h> 
of a very beautiful form ; and feems fomewhat different from the Cornijh ( ^ 
Zool. vol. IV. plate XXXVII. fig. 6), or any of the other kinds there fig l,r ^ 
But the inceffant celerity wherewith they play in the water, and the impolfibilitf 
arrefting them in an expanded ftate, evincing the difficulty of critically afcerta^ * 
their form, were an incitement to attempt it, and the chief reafon for giving ^ 
place on the annexed plate; where the general appearance of its fibrous claw^ ^ 
,a6tive tentacula, are reprefented at H'. The objedt of thefe ftridtures being n ° ^ 
much to diftinguiffi fhells by their external form, as to unfold the properties 
^economy of their living inhabitants. 
