134 



E. PH. ALLIS, The pseudobranchial circulation in Amia calva. 



Explanation of the Plate. 



Plate 6. 



I n'd ex Letters. 



aa.I afferent artery of the first 

 branchial arch 



aa. II afferent artery of the second 

 branchial arch 



aa. liy afferent arterj^ of the hyoid 

 arch 



ahy arteria hyoidea 



aps secondary afferent pseudobran- 

 chial arterj- 



CC common carotid artery 



com commissure between first and 

 second aortic arches 



dop. a dorsal opercular artery- 



ea.I efferent artery of first branchial 

 arch 



ea. hy efferent arterj- of hyoid arch 



ec external carotid 



e2)S efferent pseudobranchial artery 



h heart 



hmf truncus h^^oideo-mandibularis 

 facialis 



hop hyo-opercularis artery 



ic internal carotid. 



2^2)8 primär}^ afferent pseudobran- 

 chial artery 



2}sb pseudobranch 



2^82). a prespiracular aortic arch 



pstsp.a postspiracular aortic arch 



S2)C spiracle 



ta truncus arteriosus 



vo2^.aa ventral opercular afferent 

 arterv. 



Fig. 1. Diagrammatic representation of the first three aortic arches 

 in 6 mm embryos of Amia calva. 



Fig. 2. The same in 7 mm embryos. 



The same in 9 mm embr3'os. 



The same in 10 mm embryos. 



The same in 12 mm embryos. 



The same in 50 mm embryos. 



The same in 8 mm embryos of Le2)idosteus 0S8eus. 



The same in 10.9 mm embryos of „ „ 



The same in 26 mm embryos of ,. „ 



The same in an embryo of Pristiurus. 



Reconstruction of the first three aortic arches in a 12 mm 

 embryo af Amia calva, the mid-ventral line of the brain being assumed 

 as a base line. 



