E 
2. 
DavENPORT,— Carotids of Alligator. 
15. 
y, 
EXPLANATION OF FIGURES 
ABBREVIATIONS. 
ao. Aorta. ad mu. lar. To muscles of larynx. 
art. pul. Pulmonary artery. mu, pet. Pectoral muscles. 
dt. Bot. Ductus Botalli. (e, Ussophagus. 
ade. To esophagus. u Trachea. 
Left arteria anonyma, Rathke = ventral distributing trunk between IV. and 
III. arterial arches. 
Right ditto. 
Arteria subvertebralis colli, Rathke = a. carotis dorsalis, Mackay = third arte- 
rial arch and dorsal collecting trunk anterior to III. arch. In this vessel 
three regions may be distinguished : — 
Left vessel of the posterior paired portion, the fellow of which on the right 
side (1%) is usually lost, but in Figure 1 persists. 
H1». Fused portion of 1. (The leader should be continued to the vessel cov- 
ered by the esophagus in Fig. 1.) 
Left vessel of anterior paired (unfused) portion. 
Left collateralis colli, Rathke = a. carotis ventralis, Mackay == ventral distrib- 
uting trunk anterior to III. arch. 
Right ditto. 
Left a. subclavia == secondary or persistent subclavian (cf. Mackay). 
Anastomosing branch between 1° and 2 (== II. arterial arch ?). 
Fig. 1. Ventral aspect of head and neck regions of Alligator Mississippiensis, 
28 cm. long. Part of the esophagus and trachea are represented lying 
above (ventral to) the median artery. 
Figs. 2and 9. Lateral views of the arterial arches to show two cases of persistent 
ductus Botalli. 
Fig. 4, Diagram, showing in side view the relation of the arterial arches of Croco- 
dilia to the type. Heavy lines represent normal vessels; lighter lines, 
abnormally occurring vessels; dotted lines, vessels wholly absent in 
adult. 
