333 
Hyatt (81). In a later paper, however, he approves the terminology in- 
troduced by me, and proposes to call the development of the colony the 
astogeny (48). 
The embryonic stage of the grajitolites is represented by the initial 
portion of the sicula (first zooid), according to Ruedemann; and Holm 
(29) asserts that the more pointed end of the sicula “corresponds to the 
original chitinous covering of the free zooid germ or embryo.” This in- 
itial part of the sicula, according to Ruedemann, holds a position similar 
to the protoconch of the cephalopod shell. 
In part I of his splendid monograph of the Graptelites (48) of New 
York, at page 530, Ruedemann says: “It has been pointed out in a former 
publication that not only did there exist in the graptolites ontogenetic 
growth stages in the development of the individual zooids, 
but the rhabdosomes in toto and in their parts, the branches, seem also to 
. pass through stages which suggest phylogenetically preceding forms.” 
Of the various ways in which these astogenetic stages express them- 
selves, Ruedemann mentions the following: “The original direction of 
growth of the branches of the Dichograptids: has been in the approximate 
continuation of the sicula, i. e., an ascending erect position as long as 
the rhabdosomes were sessile, on the ground. These became pendant when 
the graptolites attached themselves in a suspended position to seaweeds, 
as numerous hydroids do today. To restore to the zooids their original 
erect position, the branches began now to recurve 
[becoming progressively horizontal, reflexed, reclined and recumbent] 
. . . We find now in the majority of the Dichograptidze with the 
above cited growth directions of the branches, that the latter still retain 
their original dependent direction, in the proximal parts in some species 
while in others by the law of acceleration, the dependent proxi- 
mal direction has already changed into a horizontal one . . . . the 
change in direction becoming progressively more abrupt as the final direc- 
tion of the branches becomes reclined . . . . or recumbent. . 
The branches pass hence, in their development, through different directions 
representing ontogenetic stages that repeat stations in their phylogenetic 
development.” (A48.) 
An analogous fact is found in the character of the thece. ‘A com- 
parison of the form of the thece of the youngest dichograptid genera 
. . . . With that of the older and presumably phylogenetically preced- 
