The Echinodermata of Shew Brunswick. 5 *^ 
the tips of which can be seen in the centre of its under side, it browses 
or grazes, according to Sir William Dawson,* along the bottom upon 
confervoid sea weeds, diatoms, sponges, and even in places the garl)age 
of the fisheries. It is quite variable, both in the form of the shell and 
the shape and color of the spines, the latter varying from violet even 
to dull white. The dead specimens so frequently found upon the 
shore, either cast up by the waves or carried up by the crows, show as 
perfectly as the most carefully prepared specimen the instructive and 
beautiful structure of the shell itself, and but little skill is needed to 
dissect out the internal organs. 
Some Sea-Urchins have the power of excavating hollows in the solid 
rock, in which they live. It is not known how they do so. This is, 
however, not done by our species, though in exposed situations they 
may be found occupying any natural hollows or crannies. In the soft 
conglomerates of parts of Passamaquoddy Bay they are sometimes to be 
seen in hollows which at first sight appear to be excavated by them, 
but careful examination generally shows that the hollows are left by 
the falling out of large pebbles from the soft matrix. Nor is our 
species of any great value as food, though this must be the species re- 
ferred to by Dr. Stimpson (see p. 20 of this paper) as edible and as good 
as lobsters when boiled. A Mediteranean species is extensively eaten 
in Ital}\ and from being cooked by boiling and eaten from the shell as 
eggs often are, has given rise to its common name of Sea-Egg. 
The course of its development from the egg is very well known. It 
has a larval stage (the Pluteus) which bears no resemblance to the adult. 
The larva has eight very long slender arms supported by calcareous 
rods, and a band of vibratile cilia, which assist it in swimming freely 
about. In about twenty-three days the Sea-Urchin begins to bud off 
from around the mouth of the larva, and as it grows the latter gradually 
disappears, being absorbed into the body of the adult. 
Order II. CLYPEASTRIDEA (Shjeld-Urchins). 
Irregular Echinoids compresned to a shield form, with the mouth central and fur- 
nished with teeth; reryhioad ambulacra, a five-leaved ambulacral rosette upon 
the upper side; very small tube- feet. 
FA MILY CLYPE ASTKID,E . 
With the edge of the disk without deep indentations. 
20. Echiiiaraclinius pariiia, (Lamarck), Gray. Ecliin- 
arachnius Atlanticus, Gray (D). [See Plate, Fig. 14]. 
“ Sand-Dollar,” ‘‘ Cake-Urchin,” 
Description. (K) p. 106, (0) p. 316. 
(“ American Naturalist,” I., 1867, p. 124.) 
