NOTE ON THE CONUS ARTERIOSUS OF MEGALOPS 

 CYPRINOIDES (BROUSSONET). 



H. D. SENIOR, M.B., F.R.C.S., 

 ASSOCIATE IN ANATOMY, WISTAR INSTITUTE OF ANATOMY, PHILADELPHIA. 



Since describing the conus arteriosus in Tarpon Atlanticus * I 

 have been fortunate in securing a specimen of Magalops cyprin- 

 oides. For this I take the present opportunity of thanking 

 Professor David Starr Jordan. 



The fish in question, preserved in alcohol, measures 19 cm. 

 (including caudal fin) so that the heart is extremely small, and is, 

 on account of its somewhat friable condition, difficult to handle. 



The conus is everywhere quite obvious from the exterior. Fig. 

 I, drawn from the left side, indicates that the general form of 



-VENTM 



FIG. i. FIG. 2. 



FIG. i. Entire heart of Megalops cyprinoides from the left side, X 3- A small 

 portion of the atrium has been removed to display the conus more fully. 



FlG. 2. Frontal section through the right side of the heart of Jilt-galops cypri- 

 noides, showing the relations in the conus region, X IO - 



conus and bulbus resembles that of Amia rather than that of 

 Tarpon. 



The heart was opened by a mid-ventral sagittal incision, it having 

 been previously ascertained that such an incision would fall be- 

 tween the valves without cutting them. After examination and 



1 BiOL. BULL., February, 1907, p. 145. (The literature on the conus arteriosus 

 is given in this article. ) 



378 



