DEPARTMENT OF MARINE BIOLOGY. 177 



On the Distribution of Marine Amehas, by A. A. Schaeffer. 



For some reason the summer of 1922 was not as favorable for the growth 

 of marine amebas in the vicinity of Tortugas and Key West as several 

 previous seasons were. Careful and continuous search brought to light only 5 

 new species of amebas, and of the 22 species previously reported from Tortugas 

 only 8 were seen this summer. The unfavorable conditions, whatever they 

 were, therefore affected the distribution of species already described as well as 

 those still unknown to science. Of the 5 new species, 2 belong to the genus 

 Thecamceba Fromentel and one each to the genera Hyalodiscus Hertwig and 

 Lesser, Cochliopodium H. and L., and Pontifex Schaeffer. The 8 previously 

 reported species, which were again seen this season, are: Cochliopodium gulo- 

 sum, Dactylosphcerium acuum, Flabellula citata, F. mira, Mayorella conipes, 

 M. crystallus, Thecamceba orbis, T. rugosa, and Trichamoeba sphcerarum. These 

 8 species and a number of others are described fully in a large illustrated mono- 

 graph now in the hands of the pubUsher. In addition to these species of 

 amebas, it may be added that 2 species of fresh-water amebas, Thecamceba 

 verrucosa Ehr. and Amphizonella violacea Greeff, were found in abundance in 

 an old abandoned cistern in Key West; and two species of Endamoeba Leidy 

 were found in the ahmentary tract of the small burrowing cockroach on the 

 Tortugas Keys, but my time was not sufficient to study these carefully. 

 About 100 cocki'oaches were examined for parasitic amebas and at least 30 

 of these bore recognizable amebas in the semi-fluid feces, which could readily 

 be squeezed from the rectum without apparent injury to the cockroach. Large 

 numbers of cihates of several species were also present as parasites in a large 

 percentage of the cocki'oaches. The larger species of Endamceba was about 15 

 microns in diameter when spherical, and the smaller species about 8 microns. 



At least 3 other undescribed species of marine amebas were observed, but 

 the number of individuals was too small for a satisfactory description. 



As soon as new species of amebas are discovered the question of their 

 distribution arises. For those that hve on bacteria one can adopt common 

 bacteriological methods to determine their occurrence. One such prehminary 

 experiment, which had for its object the determination of the distribution of 

 amebas belonging to the genus Flabellula in open sea-water off Loggerhead 

 Key, to the north, was made as follows: 



104 bottles of about 100 c. c. capacity, with cotton plugs, were sterilized in an autoclave 5 

 minutes at 15 pounds pressure. 



26 of these bottles were filled with sea-water taken about 50 feet north of the beach- 

 rock partly exposed at low tide, and a few hundred feet west of the laboratory dock. 



25 bottles were filled with sea-water taken about 0.5 mile north of the laboratory dock, 

 over beds of Thalassia, in water about 10 feet deep. 



17 bottles were filled with water 4 miles from the laboratory dock, the water being several 

 hundred feet deep at this station. Nimaerous "dust " particles floated on the surface of the 

 water. 



37 bottles were filled with water about 0.5 mile beyond station No. 3, where the surface 

 film was of average clearness. 



The bottles were carried to sea in a motor launch. At the stations specified 

 the plugs were removed and the bottles dipped in the water. Some surface- 

 film water was included in each bottle, but no attempt was made to get more 

 of the surface film than would ordinarily run into a bottle while being filled 

 with water in the upper 3 or 4 inches of surface water. The bottles were 



