42 



Phil. Enum. 156. t. 9./. 7 ?) ; quae a P. eleganti.tsima interstitiis 

 costarurn spiraliter striatis potis-simum diifert. 

 Hab. in mari Britannico rariss. vm. 



5. Parthenia pallida. Melania pallida, Phil. Enum. 157. t. 9.f. 8. 

 An Txirbo unicus, Mont. Turt. Diet. 209, &c. 



Hab. in mari Siculo (Britannico.''). 



6. Parthenia scalaris. Melania scalaris, Phil. Enum. 157. t. 9./. 9. 

 An Turbo simillimns, Laskej% Turt. Diet. 209 ? 



Hab. in mari Siculo (Britannico ?). 



The genus Turbonilla of Risso (Hist. IV. 9/24. ff. 70. and 72.) 

 appears to contain some fossil species also of Parthenia, besides the 

 recent one above referred to. Other species are indicated by Phi- 

 iippi as figured by Brocchi. 



The following paper was next read. It is entitled " Observations 

 on the Blood Corpuscles of the Snowy Owl and Passenger Pigeon," 

 by George Gulliver, F.R.S., Assistant Surgeon to the Royal Regi- 

 ment of Horse Guards. 



" Although I have found generally less difference in the blood 

 corpuscles of birds than in those of the Mammalia, yet in some of 

 the former there are peculiarities in the size and shape of the red 

 particles, which appear to me, after a careful examination of the 

 blood of upwards of two hundred different species, deserving of 

 especial attention. As examples of this kind, I select from my 

 notes an account of the blood corpuscles of the Snowy Owl and 

 Passenger Pigeon, and, by way of comparison, of one or two other 

 allied species. 



" In the following measurements, as noted in the first observation, 

 the common-sized corpuscles are first indicated ; then the small and 

 large extremes, and lastly, the average size, deduced from the whole. 

 They are all expressed in fractional parts of an English inch. 



Obs. 1. 



In the Snowy Owl (Surnia nyctea). 



Lonar Diameter. Short Diameter. 



'3 



116001 ^ 



1-1500 I Common 1-40001 Common 



1-1455 J ^'^''^' 1-4570/ sizes. 



1-2000 1 Extreme 1-5.333 1 Extreme 



1-1333/ sizes. 1-3000/ sizes. 



11 550 Average. 1-4042 Average. 



The nuclei of the corpuscles, exposed by the action of acetic acid, 

 were generally l-3200th of an inch long, and l-10666th broad. 



