I5O H. D. SENIOR. 



The conus in Tarpon appears to differ from that of Bntirinus 

 (Albuld) described by Boas ('80) in that it is less overlapped by 

 the bulbus arteriosus, and more deeply buried in the ventricle, 

 also in that it shows no diminution in length dorsally, as com- 

 pared to the ventral measurement. The two subsidiary valves 

 between the larger ones of the proximal row in Albitla do not 

 occur in Tarpon. 



The sinu-atrial valves are two, with strong tensor muscles. 

 There are four atrio-ventricular valves of which two are of large 

 size, and two somewhat smaller. The hepatic vein, at its junc- 

 tion with the sinus venosus, is of almost cartilaginous rigidity, the 

 size of the orifice is reduced by a thin fold of intima on either 

 side, these almost meet mesially to convert the circular orifice into 

 a vertical slit. The folds of intima appear to have no valvular 

 action. 



It is singular that since the appearance of Stannius's paper 

 ('46) Albula should have enjoyed the reputation of being the 

 only teleost provided with a conus having two rows of valves ; 

 whether the heart of Megalops cyprinoides will also prove to have 

 more than one row of valves is an open question. So far as I 

 am aware a description has not been recorded. 



Of the other fishes showing evidence of near relationship to 

 Aniia the following have been examined with a negative result : 

 Elops sannts by J. Mueller ('46), Hyodon by Mueller ('46) 

 and Boas ('80), Osteoglossum by Mueller ('46) and Boas ('80), 

 Notopterns by Boas ('80), Mormyrops by Mueller ('46). I have 

 also examined Elops saurns (for a specimen of which I hereby 

 beg to thank the authorities of the U. S. National Museum) 

 Hyodon tergisus and Notopterus borniensis. 



The original opinion of Gegenbaur ('66) which has been restated 

 and amplified by Hoyer ('oo) that the conus, although it has ceased 

 to exist as a separate structure in the ordinary teleost heart, is 

 represented by the portion of the myocardium adjacent to the 

 aortic valves, is well illustrated by the conus relations in Tarpon. 

 One has only to imagine the connective tissue layer between 

 the exterior of the conus and the ventricle to have disappeared, 

 allowing the conus muscle to be merged into the general myo- 

 cardium, and the transition is complete ; the relation of the myo- 



