2 MR. J. H. STEEL ON INDIVIDUAL [Jan. 6, 



Bhotan, and is said to breed in the Himala3fas ; but the examples 

 which have reached England have most likely made their way 

 hither from Siberia. It is no Swallow, but a Swift, belonging to the 

 genus of CypselidtB, to which, in 1826, the name AcanthyHs {^ro- 

 perly Acanthyllis) was applied by Boie, and Chirtura by Stephens — 

 a genus which differs from Cypselus in the structure of its foot and 

 in the spine-like tips of its rectrices. 



Dr. Mulvany, R.N., exhibited a specimen of a Penguin of the 

 genus Eudyptes, and read some remarks on it which tended, in his 

 opinion, to show that a moulting of the horny sheath of the beak 

 took place in this species. 



The following papers were read : — 



1 . Preliminary Notes on Individual Variation in Equus asinus. 

 By John Henry Steel, M.R.C.V.S., F.Z.S., Demon- 

 strator of Anatomy at the Royal Veterinary College. 



[Eeceived December 8, 1879.] 



The remarkable uniformity in external characteristics which ages 

 of neglect and degradation have conferred upon the Ass of this country 

 contrasts so forcibly with the amount of variation presented by certain 

 of our domesticated animals that some have based upon it conclui^ions 

 of a general nature tending to the admission of essential differences be- 

 tween the effects of natural selection and those resulting from arti- 

 ficial influences. For proof that these views are untenable we need 

 simply refer to the fact that on the Continent, in the East, and even 

 through quite recent artificial selection in America external variation 

 in the Ass is very marked. With regard to modification of internal 

 structures, we believe the following are worthy of note as the out- 

 come of the large number of dissections made by ourselves and 

 hy students under our supervision. We were hardly prepared to 

 observe so much variation, and were struck by many Ruminant affini- 

 ties of Equus asitius. Our observations are not arranged in a statis- 

 tical form ; nor have we occupied our time w ith minute variations in 

 bulk, length, and capacity ; we have selected those characters which 

 are most striking and at the same time most instructive. 



Osteology. 



Vertebrce, Cervical. — Atlas and Dentata : imperfect condition of 

 foramina for spinal nerves, due to arrested development. 



Seventh vertebra, Prominens : vertebral foramen may occur in one 

 or both transverse processes. 



Transverse process with costiform prolongation. This condition 

 is remarkable as showing a tendency to increase in the number of 

 the ribs. The [irocess is invariably autogenous, and not unfrequently 

 sends a styloid prolongation downwards in the adult ; but this is 



