18 THE AMERICAN NATURALIST. [Vor. XXXIV. 
employed was previously used by the elder Agassiz for ascer- 
taining the age of many marine animals (Proc. Essex Inst., 
1863), and is explained in the following quotation from the 
monograph on North American starfishes : 
“The young starfishes figured on this plate (Pl. VIII) were 
all found attached to roots of Laminaria thrown up on the 
beaches in the neighborhood after a storm; and from their 
different stages of growth, as compared with the oldest starfish 
raised from a brachiolarian (Pl. VI, Fig. 11), specimens of which 
were also found upon these roots, it is probable that the sizes 
here figured are one (Fig. 1), two (Fig. 8), and three (Fig. 10) 
years old. A considerable number of specimens were picked 
up in this way, and they could all be arranged into very dis- 
tinct groups, representing the starfishes of the present and two 
previous seasons. There seemed to be no gradation from one 
group to another, such as we have among the young sea urchins, 
which, in consequence of their manner of breeding during the 
whole year, form series the relations of which it is impossible 
to determine. In this connection I would say that, by arrang- 
ing the starfishes found upon our rocks into series according 
to their size, we are able to obtain a rough estimate of the 
number of years required by them to attain their full develop- 
ment ; this I presume to be somewhere about fourteen years. 
They begin to spawn before that time, as specimens have been 
successfully fecundated which evidently were not more than 
six or seven years old." 
During the summer of 1898 the writer had an excellent oppor- 
tunity to study the rate of growth of the starfish (Asterias 
forbesii) at a floating laboratory moored in one of the estuaries 
of Narragansett Bay. The Dreeding season was short and 
definite, and the larvae began to “set” the last of June. 
On June 29, innumerable young starfish, about as large 
as the head of a pin, were discovered clinging to the eel- 
grass and to the rockweed and other alga, where a few days, 
before none could be found. A handful of the fluffy seaweed, 
Heteromorpha, bespangled with minute stars, was placed in a 
floating car, whose sides were encrusted with a young growth 
of barnacles, fresh fronds of green algz, and delicate branch- 
