28 The Cephalic Veins and Sinuses of Reptiles 
II. THE CEPHALIC VEINS AND SINUSES OF 
TROPIDONOTUS NATRIX. 
The lterature dealing with the cephalic veins of the Ophidia includes 
a very few titles. The earliest students of the angiology of these forms, 
such as Schlemm, 27, Jacquart, 55, Nicolai, 26, and Stannius, 56, di- 
rected their attention chiefly to the arteries, and the veins were passed 
over with only casual mention. The first serious work in this field was 
done by Rathke, 39, who approached the subject from the developmental 
standpoint; he furnished an excellent account of the large venous trunks 
of Tropidonotus, including the intra-cranial sinuses, which he endeay- 
ored to homologize with those of man. Grosser and Brezina, 95, have 
reviewed Rathke’s work and verified many of his conclusions. Through 
their researches the development of the larger veins has been brought 
down to the close of embryonic life. 
According to Grosser and Brezina, the primitive arrangement of veins 
described on page 4 undergoes considerable modification in the later 
embryonic life of Tropidonotus (compare Text Fig. 1). By ring 
formation around the roots of the cranial nerves the vena jugularis interna 
shifts its position from the ventral to the dorsal side of all nerves, from 
the trigeminus backward. The vena cerebralis anterior breaks up into 
two short veins which discharge in opposite directions, the dorsal portion 
into the vena longitudinalis cerebri, the ventral portion into the 
jugular vem. The vena cerebralis media forms a new connection 
(vena cerebralis media secunda, v. c. m. s., Text Figs. 1 and 4) with the 
vena jugularis interna, and through a secondary connection (s. V., Text 
Fig. 1) communicates also with the ventral end-piece of the vena cere- 
bralis anterior. In Tropidonotus the secondary connection and the 
ventral end-piece of the vena cerebralis anterior are both intracranial. 
According to Grosser and Brezina the point of union of the two veins is 
indicated by their different relations to the ramus ophthalmicus V, the 
secondary connection lying dorsal, the vena cerebralis anterior ventral, 
to the nerve. 
The following description of the adult relations of the cephalic veins 
of 'Tropidonotus is intended to supplement the work of Grosser and 
Brezina: 
A. VENA JUGULARIS INTERNA. 
(Vena Capitis Lateralis Grosser and Brezina.) 
The vena jugularis interna of Tropidonotus (v. 7. i., Text Figs. 1 and 
4) arises from the posterior part of the sinus orbitalis, or more definitely, 
