t 440 ] 
s 
I'EsK Microfcopic Description of the Eyes of the Mono- 
culus Polyphemus linnjei. By Mr. William Andre, Sur- 
geon ; communicated by Sir Jofeph Banks, Bart. P. R. S. 
^ME Wonderful ftru&ure of the eyes of infers in 
general, mod: commonly iliuferated by that of the 
Dibellula , or Dragon -fly, cannot fail of ftriking with aflonifh- 
ment the natural if! who inveffigates the works of the oreat 
Cicatoi in his moll minute productions. According to lewen- 
hofk, hook, and others, the cornea bf moft infebls are made 
np of an infinite number of fmall, tranfparent, horny lenles, 
each lefembhng, in fome degree, a fmall magnifying glafs. 
This fit uflure prevails 111 the cornea of infects 111 general ; but 
the Monoculus Polyphemus , or King Crab , is, among others, an 
exception to this rule. 
The Monoculus Polyphemus , or King Crab , is a cruflaceous 
animal found in all the leas furrounding the continent of Ame- 
rica and the Weft India iflands, and which frequently grows to 
a very large fize *. I fhall deferibe fo much of the Monoculus 
only as is neceffary to point out the fituation of the eyes, which 
have been looked upon as two in number onlvf, though in 
reality they are four. The largefl piece of the cruflaceous 
coveiing of this animal, when leparated from the reft of the 
fhell, has very much the fhape of a barber’s bafon, or the fore- 
* I 3 ossu‘s Travels, vol. I. p. 368, 
t i-innjei Syftcma Naturae, tom. I. p. 1057. 
Read May 30, 1782. 
part 
