66 On the StruSiure of the Head of 



In tlie following inveftigation wc fliall fuppofe a i= 2 tenths of an inch, as being perhaps 

 nearly the general opening of the iris, in ftar-light nights, when the eye has been fome 

 moderate time in the dark. The value of the correclions for lofs of light will ftand as has 

 been given before. 



(To be concluded in our next.) 



VI. 



Somt Obfcrvalions ■on the Head of the Ornithorhynchus paradoxus. By Everard 



HoMiy Efq. F. R. S* 



X HE fpecimens of this extraordinary animal which have been fent to Europe, have 

 been deprived of the internal parts, and the fkins are moftly dried, and but badly preferved. 

 Such imperfe£l fpecimens have raifed the curiofity of the naturalift, and excited the ardor 

 of the anatomift, without fatisfying their enquiries. 



It was natural, under thefe circumftances, to referve any obfervations which had been 

 made upon this newly difcovered quadruped, till the entire animal (hould be brought home 

 preferved in fpirit, and enable us to examine the ftru£lure of its different organs ; but, 

 finding that Profeflbr Blumenbach has been led to believe that it was an animal without 

 teeth, an opinion which muft have -arifen from the imperfe£l ftate of the fpecimen he 

 examined, it appeared highly proper to do away the miftake, and lay before this learned 

 Society, fuch obfervations refpeSing the head of this extraordinary animal, as I have been 

 enabled to make. 



My opportunities of examining the Ornithorhynchus were procured through Sir Jofeph 

 Banks; who permitted me to have drawings made from the Ikin of one of a very large 

 fize, and which, from having been preferved in fpirit, was more perfedl than any of the 

 flried fpecimens. 



Any general defcription of the beak of this animal, which is its moft confpicuous 

 peculiarity, becomes unneceffary, as the accompanying drawings will give a fufliciently 

 correft idea of the outward appearances, to anfwer the prefent purpofe. 



It was not permitted to examine the head anatomically ; but a fmaller dried fpecimen, 

 received from Sir Jofeph Banks, furniflied me with the following obfervations. 



The beak of the Ornithorhynchus^ when It is curforily examined, appears fo ftrongly to 

 refemble that of the duck, as to lead to the belief of its being calculated for cxa£lly the 

 fame purpofes ; It will however be found to differ materially from it, in a variety of 

 circumftances. 



The beak Is found, upon examination, not to be the animal's mouth, but a part added 



to the mouth, and projedting beyond it. 



* Philofophical TrrmfafUons i&qo. 



The 



