90 



BULLETIN OF THE BUREAU OF FISHERIES. 



empty, unci communicates with the auricle by the large sinu-auricular opening, which 

 is guarded by a two-lipped valve. The auricle is large, thin-walled, and situated 

 cranial to the sinus and slightly cranial and dorsal to the ventricle. Its lateral angles 

 project somewhat ventrad upon the sides of the bulbus arteriosus, and it opens into 

 the ventricle by the auriculoventricular aperture, which is a transverse, elliptical 

 opening with a two-lipped valve. The ventricle is thick-walled, and shaped like a 

 triangular pyramid with the apex directed caudad. The bulbus arteriosus, which is 

 quite large, extends craniad from the base or cranial portion of the ventricle, and 

 tapers into the ventral aorta. The valve between the ventricle and bulbus consists 

 of two segments and is of the usual semilunar type. According to Boas (1880), the 

 small region between the bulbus and ventricle, in which the valve is situated, corre- 

 sponds to the conns arteriosus of the elasmobrauch heart. 



• 



THE ARTERIES. 

 THE VENTRAL AORTA AND THE AFFERENT BRANCHIAL ARTERIES. 



The ventral aorta (tigs. It; and 18, pi. I) extends craniad as a continuation of 

 the bulbus arteriosus, and after giving off, in the order named, the fourth, third. 



Fig. 1.— Efferent branchial vessels of tile-fish (Lnpholatilus charmdeanticeps) , with cireulus 

 cephalicus. Ventral aspect, natural size. On the left side the hyoidean and afferent 

 pseudobranchial arteries are shown: on the right side the efferent pseudobranohial 

 artery. 



and second pairs of afferent branchial arteries, bifurcates at its cranial end to form 

 the first pair of afferent vessels. On each side the third and fourth afferent branchial 

 arteries arise from a common stem. The second pair arise as separate vessels. 



THE EFFERENT BRANCHIAL ARTERIES. 



The efferent branchial arteries (i to iv, tigs. 16 and IS, pi. i) correspond pair 

 lor pair with the afferent vessels just described. They converge, one from each gill 



