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On THE REGULATION OF THE SUPPLY OF BLOOD TO THE VENOUS SINUSES OF 
THE HAD OF REPTILES, WITH DESCRIPTION OF A NEW SPHINCTER 
MUSCLE ON THE JUGULAR VEIN. By H. L. BRuNER. 
[Abstract.| 
The remarkable development of blood sinuses in the reptilian head has 
received no explanation at the hands of earlier investigators. The work 
of the writer shows that the origin of these sinuses is due to periodical 
constriction of the jugular vein by a ring-like muscle, whose contractions 
thus lead to an increased blood pressure in the region drained by the vein. 
In Phrynosoma this ring-muscle, which is composed of striated fibres, 
is attached to the lateral end of the ex-occipital bone, beneath which the 
jugular receives the posterior cerebral vein. Immediately behind the 
mouth of the latter vein, the ring-muscle embraces the jugular. The 
muscle occurs also in turtles (Hmys) and snakes (Tropidonotus). 
According to the observations of the writer on lizards, the distention 
of the extra-cranial blood sinuses is of great importance at the time of 
moulting, when the removal of the old epidermis is greatly facilitated by 
it, particularly in the region of the eyes and nasal openings. Under or- 
dinary circumstances, such distention probably serves to express emotion 
of various kinds. 
The above-mentioned facts furnish a basis for an explanation of the 
habit of ejecting blood from the eye (orbital sinus), for which Phrynosoma 
is noted. 
For additional details, the writer refers to the paper itself, which will 
be published in full elsewhere. 
Nore oN THE ABERRANT FOLLICLES IN THE OVARY OF CYMATOGASTER.* 
By GrorGce L. MircH eu. 
The thickness of the ovarian follicle varies in different vertebrates in- 
versely with the size of the egg. In species containing large eggs the 
thickness of the follicle decreases relatively with the growth of the egg. 
In the bird and frog it is only in the smaller eggs that the single layer 
of follicle cells may be distinguished in sections. The rapid growth of the 
egg soon stretches this layer of cells so that it becomes finally indistin- 
*Contributions from the Zovlogical Laboratory of the Indiana University, No. 25. 
