62 PROCEEDINGS OF THE ACADEMY OP [1886. 



probability arises that they will be left high and dry on the shore, 

 the}^ can appreciate the fact b}'' the growing intensity of the light, 

 and by that peculiar flapping motion of the valves the Pectens 

 are so remarkable- for, move away into deeper water.' This 

 theory may at once be set aside when we consider that the Pec- 

 tens of the Mediterranean, where we have practically no tide at 

 all, a state of affairs that has existed for an exceedingly long 

 period of time, have as well developed eyes as those found on 

 shores where tides do exist ; and further, it seems hardly probable 

 that such a complicated organ would have developed to detei'- 

 mine for the animal whether it be out of water or not. . . . As 

 regards the complicated organ known as the eye, I might suggest 

 that, if this be an eye, it is one where we have no true pigmented 

 laj^er in any direct relation to either the nerve or the retina. The 

 mass of red pigment and the metallic-like tapetum would hardly 

 answer the place of the black choroid coat so essential to the 

 eye." 



Dr. Sharp stated that at the time the above was written, he 

 was under the impression that the organ was probably a phos- 

 phorescent organ, but he had no proof of it. At Nantucket he 

 obtained many specimens of the animal and. found that the edge 

 of the mantle was phosphorent, and on questioning Dr. Kite, 

 formerly of the " Fish-Hawk," who had often seen Pecten dredged 

 at night, he was informed that the phosphorent condition of Pec- 

 tens had often been observed. He thought it was not unreasona- 

 ble to suppose that organs for the emission of light should be 

 formed upon the same general principles as organs for the admis- 

 sion of light, hence the similarity of these organs to eyes. He 

 further stated that this function (phosphorescence) would be of 

 great use to the animal in obtaining its food. 



On Amia and its probable Taenia. Prof. Leidy stated that in 

 our market on Saturday last, three Mud-fishes, Amia calva, had 

 been given to him. They came in a barrel of shad from North 

 Carolina. One was a female about two feet long, the others male, 

 of which the smallest was eight inches. Protruding from the 

 vent of the latter was a little tape-worm, which, on disturbance, 

 retreated into the rectum. Three other worms of the same kind 

 were found in the mouth, but none were in the intestine of this or 

 the other fishes. The worms accord with the description of the 

 Tsenia filicolis, infesting Sticklebacks, Gasterosteus, and is prob- 

 ably the same species. They range from 1^ to 3 inches long, 

 gradually widening from the delicate thread-like neck to the pos- 

 terior rounded extremity where thc}^ measure from ! to TS mm. 

 wide. The head is spheroidal, variably broader or longer, and 

 about 0'625 mm.; with the summit slightly prominent and 

 unarmed, and with four hemispherical, lateral bothi'ia 0'25 mm. 

 in diameter. Neck variable ; when extended, long and narrow and 

 usually about half the width of the head. Anterior segments, 



