September 9, 1910] 



SCIENCE 



349 



effect is produced on the partbenogenetic 

 females. D. D. Whitney 



Wesleyan Univessitt, 



MiDDLETOWN, CONN., 



August 15, 1910 



j a report ox the fresh-water protozoa op 

 Tahiti' 



The following brief report is a result of 

 some work done upon the protozoa of Tahiti 

 during the months of July and August, 1908. 



An oceanic island is always an interesting 

 field for the investigation of the higher forms 

 of animals, because of its faunal peculiarities 

 or deficiencies, but a valid question arises, 

 namely, may we expect these same peculiari- 

 ties or deficiencies to exist with respect to 

 animals of the lowest rank? 



So far as the writer has been able to de- 

 termine, no list of fresh-water protozoa of a 

 mid-ocean island has previously been reported. 



Tahiti, the largest of the Society group, is 

 situated 17A° south latitude, 149^° west 

 longitude. It is a high island of over 400 

 square miles, of volcanic origin, more or less 

 densely covered with a tropical vegetation, 

 ilountains of the interior reach a height of 

 nearly 8,000 feet, and numerous streams of 

 fresh water flow down the valleys across the 

 narrow plain to the sea. 



During the winter months of July and Au- 

 gust, in Tahiti, the small streams are in a 

 low condition, it being the dry season, and 

 many of them are choked with plants of low 

 orders, which would apparently be a fit con- 

 dition for the presence of a rich microscopic 

 fauna. 



During the brief time allotted to the study 

 of the protozoa, collections were made in 

 many places from the waters of this border 

 zone a few yards from the sea and from its 

 level to a few feet above. 



In all, forty-four species were observed and 

 studied with considerable care. Of these, 

 thirty-six were positively identified, and eight 

 referred to their proper genera, but the 

 species undetermined. 



' Read before the Central Branch of the Amer- 

 ican Society of Zoologists at Iowa City, April, 

 1910. 



Of the thirty-six species identified, nine 

 were of the class Sarcodina, six of the class 

 Mastigophora, and twenty-one of the class 

 Infusoria. Of the undetermined species, two 

 were rhizopods and six ciliates. 



All of the thirty-six species studied in Ta- 

 hiti are more or less common in the waters of 

 this state; twenty of them have been reported 

 from Boulder, Col., by CockereU; and nearly 

 all of them from Connecticut by Conn. 



Penard, in the American Naturalist for 

 December, 1891, lists thirty-six species of 

 rhizopods found in the Rocky Mountains near 

 Caribou, Col., at a height of 10,000 feet, and 

 thirteen species at 12,000 feet. Of the thirty- 

 six species listed by Penard at an elevation of 

 10,000 feet, sis species were found in tropical 

 Tahiti within a few feet of the level of the 

 sea. Of the thirteen species listed by Penard 

 found at an elevation of 12,000 feet, one Dif- 

 flugia pyriformis, is a rather common rhizo- 

 pod in Tahiti at sea-level. 



Penard calls attention to the fact that the 

 rhizopoda of higher altitudes are those with 

 lobe-like pseudopodia, the forms with ray- 

 like pseudopodia being absent. It may be 

 added that the predominating rhizopods of 

 the sea-level are also of the lobose type, and a 

 majority are protected by shells. Only one 

 species of rhizopoda with ray-like pseudo- 

 podia was found in Tahiti. 



Taking as a basis the list of protozoa re- 

 ported by Stokes in 1888, the list reported by 

 Conn in 1905, and the list of the writer in 

 1906, it is quite safe to say that the relative 

 proportion of the protozoa for the United 

 States of the three classes (sporozoa not in- 

 cluded), is approximately as follows: Sarco- 

 dina, 15 per cent.; Mastigophora, 25 per cent., 

 and Infusoria, 60 per cent. 



Taking forty-four species of Tahiti as a 

 . basis, the proportion is as follows : Sarcodina, 

 25 per cent.; Mastigophora, 14 per cent.; In- 

 fusoria. 61 per cent. 



It would seem from these observations that 

 the proportion of infusoria reported in the 

 oceanic island holds true to that of the 

 United States, a variance appearing in the 

 case of the other groups. 



Among the pseudopodia-bearing forms, Ar- 



