248 



SCIENCE. 



[N. S. Vol. XIX. No. 476. 



estimated number of fishes eaten in this 

 region by terns in the course of one day is 

 estimated by Mr. Jones as follows : 



Per Cent. 



Ammodytes americanus 80 736,000 



Tautogolahrus adspersus 8 73,600 



Mugil curema 4 36,800 



Pollachius virens 3 27,600 



Clupea or Pomolobus 3 27,600 



Pseudopleuroneotes americamis . . . . 2 18,400 



100 920,000 



Mr. Jones concludes that the number 

 of food fishes consumed by terns is a 

 negligible quantity. The food of the gulls, 

 loons, kingfishers, osprey and ducks was 

 not studied. 



Austin P. Larrabee, A.M., graduate stu- 

 dent. Harvard University: 'The Effect of 

 Heredity on the Dimorphism exhibited in 

 the Optic Chiasma of Teleosts.' 



Edwin Linton, Ph.D., professor of biol- 

 ogy, Washington and Jefferson College: 

 'Investigations on the Parasites of Pishes' 

 (conducted for the bureau). Prom Au- 

 gust 13 to September 6, about 150 fishes, 

 representing 32 species, were examined. 

 In addition to this, a preliminary examina- 

 tion was made of material which had been 

 collected by Mr. Vinal N. Edwards at vari- 

 ous times during the past four or five years, 

 comprising parasites from 27 species of 

 fish and two mammals. The greater part 

 of this collection consisted naturally of 

 comparatively large and common species of 

 parasites. In some cases, however, where 

 the entire viscera had been preserved in 

 formalin, many small and rare forms were 

 found which would certainly have been 

 overlooked by the general collector. 



The plan of investigation of the fresh 

 material consisted in making careful search 

 for parasites in the alimentary tract and 

 body-cavity, on the gills and occasionally 

 in the muscular tissue of the fish. So far 

 as time would admit, sketches and meas- 



urements were made, especially of varying 

 states of contraction in the soft-bodied 

 forms. Note was also made of the color, 

 relative abundance, place of occurrence in 

 the host, etc. ; and particular attention was 

 given to diseased conditions resulting from 

 the presence of parasites. The nature of 

 the food was also noted, since the character 

 of the food may sometimes furnish a clue 

 to the discovery of the intermediate host. 



Thus far but little has been accomplished 

 in working out the life history of the para- 

 sites of fishes. Some hint of the source of 

 infection may be obtained by noting the 

 relative abundance of parasites in the dif- 

 ferent seasons of the year. For this rea- 

 son, such collections as those of Mr. 

 Edwards are especially valuable. 



Of forms which are new, or at least 

 which have not been reported before, 

 there were found: One species of the order 

 Acanthocephala, two of the order Nema- 

 toda, six of the class Trematoda, and four 

 of the class Cestoda. The results of this 

 summer 's work will be made the subject of 

 a special report. 



Joseph A. Long, graduate student. Har- 

 vard University: 'The Reaction of Eyeless 

 (Blinded) Pish to Light.' The fish used 

 were Fundulus majalis and F. heteroclitus. 

 By using an aquarium provided with an 

 electric light, and covered with black cloth 

 in such a way that one half was darkened 

 and the other half was in bright light, it was 

 found that normal fish in good condition 

 were decidedly phototropic in a positive 

 way. After observations had been made 

 on the normal fish, the optic nerves were 

 cut, and the previous experiments repeated. 

 No evidence was found that in Fundulus 

 there were sense organs in the skin or 

 lateral line that were responsive to light. 



M. C. Marsh, pathologist of U. S. 

 Bureau of Pisheries: 'The Causes of the 



