NILS ROSE^", STUDIES ON THE PLECTOGNATHS. 



15 



also originates from the ventral ends of the efferent bran- 

 chial arteri es is arter ia coronaria. I ha ve not been able to 

 find this artery in Spheroides, but, owing to the fact that 

 neither the microscopical slides nor the dissected larger spe- 

 cimens have been injected, such a small vessel may easily 

 have been overlooked. As the mode in which arteria coro- 

 naria is supplied with blood in Orthagorisciis, according to 

 Milne-Edwards and G. H. Parker differs from that one in 

 other Teleosts, it wonld have been of interest to know the 

 condition in some other Plectognaths. Milne-Edwards has 

 shown and his statements have been verified by G. H. Par- 

 ker, that in Orfhagoriscus the coronary artery receives its 

 blood from both the first, second, third and fourth efferent 



iP^ig. 10. Part of arterial System of SjDheroides testudineus. a, aorta ; cm, 

 arteria coeliaco-mesenterica; /•, arteria renalis; s, arteria subclavia; 1 — 10, 

 arteries supplying the air-bladder (i), the spleen (2), the Ii ver {5), the sto- 

 mach {4), the intestines {3, 6 — 9), the gonads (10). 



branchial vessels, as in the Elasmobranchs. In all other 

 Teleosts only the second pair suppJies the coronary artery, 

 according to these authors. In the Loricati, studied by 

 Allén, however, even the third pair is engaged in supplying 

 the coronary artery. Certainly, Orthagoriscus shows undeni- 

 ably in this respect a very primitive character. 



Arteria subclavia does not show any differences amongst 

 the Plectognaths as to its origin. Both arteries arise just 

 at the base of the aorta (Fig. 7 and 8 s). 



Arteria coeliaco-mesenterica (cm). In Lactophrys (Fig. 8 a), 

 Diodon (Fig. 8 b), Spheroides (Fig. 8 c) and Tetrodon (Fig. 7 b) 

 this artery arises at the base of the aorta a little to the 

 right. In Balistes (Fig. 7 a) it takes its origin from the com- 

 mon part of the united third and fourth right efferent bran- 



