| OCR Text |
Show 2 MR. J. H. STEEL ON INDIVIDUAL [Jan. 6, Bhotan, and is said to breed in the Himalayas; 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 Cypselidce, to which, in 1826, the name Acanthylis (properly Acanthyllis) was applied by Boie, and Chcetura 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 H E N R Y STEEL, M.R.C.V.S., F.Z.S., Demonstrator of Anatomy at the Royal Veterinary College. [Received 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 conclusions of a general nature tending to the admission of essential differences between the effects of natural selection and those resulting from artificial 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 outcome of the large number of dissections made by ourselves and by students under our supervision. W e were hardly prepared to observe so much variation, and were struck by many Ruminant affinities of Equus asinus. Our observations are not arranged in a statistical form ; nor have we occupied our time with 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 vertebrce, 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 process is invariably autogenous, and not unfrequently sends a styloid prolongation downwards in the adult; but this is |
