335 
In Goniocidaris the interambulacral plates of the adult are approx- 
imately hexagonal in form instead of pentagonal. “The relative form 
of the plates in young Goniocidaris is almost exactly the same as in the 
primitive type, Bothriocidaris.” 
“The early stage in which we find a single interambulacral plate, to- 
gether with two ambulacral plates, in each area is so important that it 
is desirable to give it a name, the protechinus stage. The protechinus is 
an early stage in developing Echini, belonging to the phylembryonic period, 
in which the essential features of the echinoid structure are first evinced. 
. . . . This protechinoid stage of Echinoderms is comparable as a stage 
in growth to a similar stage which is expressed in the protegulum of 
brachiopods, the protoconch of cephalous mollusks, the prodissoconch of 
pelecypods, and the protaspis of trilobites.” (33.) 
Miss Smith (Mrs. Alexander Shannon) has shown very conclusively 
the exact resemblance of the form of the young Pentremites conoideus to 
the adult Codaster (52). In Codaster the conical form, narrowest at the 
base and enlarging upward, is maintained throughout life. In Pentremites 
only the early stages of growth have this form, while the adult is broadest 
at the base and narrowest at the top. 
This evidence from development would, according to the theory of 
recapitulation, indicate that Codaster stands in an ancestral relation to 
Pentremites, and it is therefore of importance to the theory that Bather 
(2) from other evidence has independently reached the same conclusion 
as Miss Smith in regard to the relationship of the two forms. 
Among corals Beecher (5) has worked out the development of Pleu- 
rodictyum lenticulare and concludes that the first neanic stage, in the 
manner of growth and the structure of the corallum, is very suggestive of 
, 
Aulopora, and should be given considerable significance.” Girty (21) comes 
to the same conclusion from a study of Favosites forbesi, ete. 
Bernard (14) has shown that the coral cclony in similar fashion to 
the bryozoan colony and the graptolite colony behaves as an individual. 
In another paper (15) he has recognized as the first growth stage of the 
'Bather’s conelusicn was published in 1990, and Miss Smith’s paper in 1906. 
The latter, however, was not aware of Bather’s views as to the relationships of 
these two forms, so that the conclusions of the two workers, arrived at indepen- 
dently and from different lines of evidence are all the more important and conyine- 
ing. Bather says in a review of Miss Smith’s paper that he considers Pentremites 
as the “‘extreme link in the series Codaster—Phaenoschisma—Cryp toschisma—Oroph- 
ocrinus—Pentremitidea—Pentremites.”’ 
