198 CARNEGIE INSTITUTION OF WASHINGTON. 



Mar. Biol. Assn., vol. 12, 339-336, 1920), but the latter field, except in the 

 case of corals, has not been touched previously. 



Small rafts of various sizes, mostly of Oregon cedar, were attached singly 

 and in series to buoys in the harbor of Pago Pago and examined constantly. 

 The succession of animals settling and growing thereon was observed, and 

 at definite intervals one of a series of rafts was removed to the laboratory 

 to be photographed and preserved. Other experiments were with small 

 cages, the sides of which were made of sheets of perforated zinc, with planks 

 weighted so as to hang vertically, and with glass plates carried underneath 

 small wooden rafts. 



Rich growths of hydroids, compound tunicates, polyzoa, colonial serpulid 

 worms, and barnacles were established very quickly on the under surface of 

 the rafts. Within 3 weeks the wood was completely covered by the colonies. 

 The wood-boring lamellibranch Teredo was invariably among the first colonists, 

 and in less than a month the wood was riddled by its burrows. 



The most definite results were obtained in the case of the goose-barnacle 

 (Lepas), a valuable genus for comparison, since its species are scattered widely 

 over the world. In 19 days after the rafts had been placed in the sea the ends 

 were fringed with barnacles of a considerable size, producing Nau-plius larvae. 

 After attaining sexual maturity, the growth-rate slows down, but in one case 

 full size was nearly attained within a period of 50 days. Observations of the 

 time required to attain sexual maturity were also made on Teredo (which pro- 

 duces larvse within 24 days), the hydroid Pennaria, the compound tunicate 

 Leytodinum, and serpulid worms. 



The rate of growth of colonies was best studied in cases like the serpulid 

 worm Filigrana and in some Polyzoa. 



A period from the middle of May to the end of July was available for con- 

 tinuous observation, but even this was seriously curtailed by heavy rains which 

 caused great mortality among the animals growing on the rafts. The facts 

 recorded must therefore appear scanty compared with those gathered by a 

 resident observer in temperate regions, but the cases cited above show that in 

 all probability some animals, like Lepas and Teredo, living in a constant tem- 

 perature of from 26° to 30° C, grow at a considerably greater rate and become 

 sexually mature very much earlier than their alhes in northern waters; in 

 others, like hydroids and colonial tunicates, the processes of growth and 

 maturation do not seem to be greatly accelerated. 



Marine Algce and Terrestrial Plants of Tutuila, Samoa, by Williain A. Setchell. 



The main object of my visit to the island of Tutuila (May 31 to July 28), 

 was to make observations on, and collect specimens of, the incrusting and other 

 species of marine algae to be found on the coral reefs of the island, in order that 

 their identity might be more thoroughly established than has been done pre- 

 viously. As intimately connected with this intention, it seemed best to 

 attempt to collect and study all other marine algse and to determine their 

 relation, if any, to those of the reef, and the ecology of both. 



Somewhat distinct from these objects, but as having a bearing on the general 

 study of the island and its reefs, it seemed best to make such a reconnaissance 

 of the land flora and of its ecologic relations, both general and special, as might 

 be possible during the Hmited time of my stay. An attempt was made, 

 therefore, to collect all species possible, to learn their Samoan names and uses, 

 and particularly to determine the distribution of each species and to obtain 

 the data for arranging them in their proper belts, formations, associations, etc. 

 With the assistance of Siitupe, a native of the village of Pago Pago, about 36 

 years of age, and apparently very well acquainted with the plants of the 



