388 Harris Hawthorne Wilder 



adherent to the heart, and the left one is especially reduced, yet both 

 possess the normal number of lobes [Fig. 17]. From each ventricle an 

 aortic arch proceeds to the dorsal aorta of the component to which the 

 ventricle belongs, that from the right ventricle passing to the aorta of 

 B, and that from the left to the aorta of A. The first of these has been 

 described before in connection with the heart of the other side. From 

 the arch that arises from the right ventricle (B's), anatomically a pul- 

 monary arch, there arises an innominate artery that divides into the caro- 

 tids of the synotic side, and as this supplies an A moiety it balances the 

 condition upon the other side where a carotid from the A component 

 supplies a moiety belonging to B. The two aortic arches in question, 

 although each is plainly given off from the ventricle indicated, yet 

 possess a common trunk along the region of the semilunar valves, and it is 

 from this that the two pulmonary arteries are given off. The pulmonary 

 veins are represented, much as in the other heart, by two openings into 

 the left atrium, as seen in Fig. 16, in which this chamber is repre- 

 sented as cut open. The two venae cavte open into the right atrium as 

 normally. 



A general idea of the relations of both hearts and the main blood-vessels 

 may be learned from an inspection of the accompanying diagram [Fig. 

 18]. In this the view is taken a little obliquely, with the hearts at 

 slightly different levels, in order to show the parts better. This brings 

 the vessels on the two sides of the common neck at an unnatural distance 

 from each other, and necessitates a lengthening of the aortic arch that 

 runs between the lesser heart and the aorta of component B. Other- 

 wise the proportions are not far from actuality. 



The data shown in this diagram may be put into synoptical form as 

 follows : 



1. Four aortic arches, one from each ventricle. Of these the most 

 abnormal is that from the right ventricle of A. Had that arch gone in 

 the opposite direction and entered A's main aortic trunk we would have 

 a symmetrical condition, probably the typical one for such monsters, in 

 which each aorta would be formed by the union of arches from the two 

 ventricles originally belonging to its respective component. Of these 

 arches those from the right ventricles are naturally the pulmonary arches 

 and give rise to the pulmonary arteries. Their connection with the other 

 arch is of course through the ductus Botalli. 



2. Four pulmonary arteries, two from each heart. In the greater 

 heart these proceed from the aberrant aortic arch, contributed by the right 



