The Echinode'.'r.zata of Jhew Q^rmiswick. 47 
therefore, in a general way, according to the age of the animal. In 
specimens less than one inch in diameter the length of the ray is less 
than twice the diameter of the disk. In a specimen four inches in di- 
ameter, the ray is nearly three times as long as the diameter of the disk, 
while in the very large specimens above mentioned it is nearly three and 
a half times. The rays taper evenly from base to tip, except in the 
breeding season, when they are enlarged at the base. The ambulacral 
furrows are narrow and can be completely closed in by the bringing 
together of their sides. 
Its spinulation is cpiite simple. To the naked eye the whole of the 
upper and the most of the under surface present a uniformly granular 
appearance. A good lens, however, will show that these granules con- 
sist in reality of clusters of spines borne upon low tubercles. But the 
clusters var}- greatl}' as to the number, shape and size of the spines on 
different }>arts of the surface of the body. Among the spine-clusters 
may be seen in dried specimens little holes, which in the living animals 
may be seen to be occupied, each by a delicate projection of a clear 
membrane from the interior of the body. These are the papuUe or 
water-tubes, the function of which is not certainly known, but is supposed 
to be respiratoiy. It is the dotted or “eyed” appearance presented by 
these organs which is supposed to have suggested to Linck the name 
oculata which he gave to it and which is still used by some naturalists. 
Upon the under surface the spine-clusters grow somewhat larger as they 
approach the ambulacral furrows. Upon each side of the latter there 
runs from the mouth to the tip of the ray a row of clusters, flattened at 
right angles to the length of the ray, of ver}" much larger spines ; these 
spines are arranged in the cluster in a double row and are largest on the 
edge of the furrow, growing rapidly smaller away from it. Inside of 
this row, indeed quite within the furrow, is another row of apparently 
single spines. The mouth-plates are rather small and the spines they 
bear not appreciably larger than those along the ambulacral furrows 
In color CrihreUa varies greatly, but is always bright. The under side 
is usuall}' light ^^ellow or straw colored, and the upper some shade of 
red or purple, or even yellow or orange. These colors, as in other Star- 
fishes, are more or less due to differences of sex. In the case of the 
two large specimens above mentioned, found at L’Etang, the larger, 
which proved upon dissection to be a male, was a dull purplish red 
above, and the smaller, a female, a bright orange. Prof. Alexander 
Agassiz expre.sses the variation in this species very vividly when he says: 
“This pretty little Starfish presents the greatest variety of colors; some 
are dyed in Tyrian purple, others have a paler shade of the same hue, 
.‘^onie are vermili?hi, others a bright orange or yellow. A glass dish 
filled with Cribrellae might vie with a tulip-bed in gayety and vividness 
of tints.” 
