ON THE MORPHOLOGY OF THE VERTEBRATE- 
SKULE. 
Dr. G. BAUR, 
New Haven, Conn. 
Ey Lae, “Orc ELEMENTS: 
In this article attempts will be made to show that the doc- 
trine of the “otic” bones established by Professor Huxley 
twenty-five years ago, and held since that time by nearly all 
morphologists, is incorrect. The material upon which these 
notes are based consists of the skulls of Lepzdosteus, Amita, 
Necturus, Mastodonsaurus, Chelone, Ichthyosaurus, Sphenodon, 
Didelphys. Taking Chelone as a central form, I shall then 
examine first the higher and afterwards the lower types. 
In Chelone the foramen magnum is bounded laterally by the 
exoccipitals ; to these bones the paroccipitals (Owen), opistho- 
tics (Huxley) are united by suture on the outside. In front of 
the paroccipitals another pair of bones is found, the petrosals 
(Owen), proédtics (Huxley). The supraoccipital joins the paroc- 
cipitals and petrosals, forming the characteristic Y-shaped fig- 
ure. Between the paroccipital and the petrosal at the lower 
side, the stapes is placed, which is small in comparison with the 
surrounding bones. 
In /chthyosaurus! we have about the same conditions: the 
petrosal is a small bone; there are no true sutures between this 
element, the paroccipital, and supraoccipital, they are all sepa- 
rated by cartilage, which is very much more developed than in 
Chelone. The stapes is exceedingly large, surpassing in size not 
only the petrosal, but also the paroccipital; it is placed be- 
tween paroccipital and petrosal below. 
In Sphenodon we have a corresponding arrangement. In the 
1 My observations on Ichthyosauria are mainly based on the splendid material in 
the collection of Mr. A. N. Leeds of Eyebury, near Peterborough, England, in which 
the elements of the skull are separated. I have to thank Mr. Leeds very much for 
his great kindness and hospitality, shown to me during a visit two years ago. 
