46 The Cephalic Veins and Sinuses of Reptiles 
In later stages, when this part of the parotic process ossifies to form the 
lateral extremity of the occipitale laterale, the majority of the muscle 
fibers are attached to that bone (Ol., Fig. 3, Plate 1), while the re- 
mainder arise from a membrane bone, the supra-temporale (S¢t.), which 
covers the lateral part of the parotic process. From their origin the 
muscle fibers extend mesad and somewhat caudad, partly above, partly 
below the vena jugularis interna. The larger number of these fibers, 
both dorsal and ventral, insert on the crista epibranchialis (C. ep., Text 
Fig. 7; Fig. 3, Plate I); the remaining fibers envelope the vein, the 
anterior fibers coiling forward, the posterior fibers backward, from their 
origin. The free fibers of the musele are either spiral or longitudinal 
in direction, the spiral fibers being mixed with those which spring from 
the parotic process, while the longitudinal fibers lie for the most part 
inside of the spiral fibers next to the lumen of the vein. 
The stronger anterior part of the muscle includes a total of four or 
five layers of fibers, which form a close covering for the vein as far 
caudad as the mouth of the vena cerebralis posterior. Behind this point 
the muscle is less compact and contains a large proportion of longitudinal 
fibers. On the whole the constrictor muscle is not so strongly developed 
in Lacerta as in the other forms already mentioned. 
In addition to the species referred to, the m. constrictor venze jugularis 
interne has been anatomically demonstrated in the following forms: 
Agama colonorum Daudin. 
Moloch horridus Gray. 
Uta stansburiana Baird and Girard. 
Anolis caroliniensis Cuvier. 
Sceloporus undulatus Latreille. 
Anguis fragilis Linnaeus. 
Lacerta viridis Linnaeus. 
Lacerta muralis Merr. 
Cnemidophorus sexlneatus Linnaeus. 
In all of these forms the constrictor muscle is well developed. It 
arises in all cases from the parotic process, chiefly from the ossified 
crista parotica (occipitale laterale), and when the second epibranchial 
cartilage is present, the median part of the muscle is attached to it. I 
have found this attachment in the Teiide (Cnemidophorus) and Igua- 
nidee (Sceloporus), as well as in the Lacertide.’ 
* According to Cope, 98, free epibranchials occur also in the Scincide and 
Xantusiade, but no representatives of these families have been studied. 
