244 PROFESSOR MARSHALL AND EDWARD J. BLES. 



the mandibular arch the efferent branchial vessel and the diverticulum 

 from the aorta are present, but that the afferent branchial vessel 

 and the diverticulum from the truncus arteriosus are not present at 

 any stage ; i.e., that the vessels of the mandibular arch are so far 

 comparable to those of a branchial arch as to indicate the ancestral 

 presence of gills, but that the modifications undergone by the man- 

 dibular arch are more profound than those of the hyoid arch. A 

 further difference between the mandibular and hyoid arches lies in the 

 fact that while the vessels of the latter disappear completely, the 

 aortic diverticulum of the mandibular arch persists as the pharyngeal 

 artery. 



Concerning the lingual artery, we have looked out very carefully 

 for any evidence of its belonging to either the mandibular or hyoidean 

 arches, but have entirely failed to find such. 



The earliest date at which we have found the lingual artery is 

 about 8| mm., when it has relations similar to those shown in a 

 9 mm. tadpole in Fig. 11, A L, but is of rather smaller size. In the 

 frog it appears therefore to arise late in development, and to be at 

 first independent of all other vessels. While satisfied as to the 

 correctness of this account, we are not disposed to attach much 

 importance to it from a morphological standpoint. The mode in 

 which the lingual artery becomes connected with the ventral end of 

 the first branchial efferent vessel strongly suggests that the actual, 

 ontogenetic, development is a modified one. The bulb-like swelling 

 on the lingual artery, which is present from its first appearance, is a 

 curious feature for which some explanation is wanted. 



Turning now to the accounts given by other investigators of the 

 development of the vessels in the mandibular and hyoidean arches 

 of Amphibians, both Goette and Maurer have given somewhat brief 

 descriptions. 



Goette* describes in Bombinator a small vessel as developing in the 

 hyoid arch subsequently to the branchial vessels, and acquiring a 

 connection dorsally with the dorsal aorta or carotid artery just in 

 front of the ear ; while ventrally it joins the first afferent branch of 

 the truncus arteriosus. This vessel therefore forms a complete arch 

 connecting the truncus arteriosus and the aorta directly. It soon, 



* Goette, A., " Entwickelungsgeschichte der Unke," pp. 756, 757, and plate xxi., 

 Fig. 377. 



