260 THE OCEAN WORLD. 
thoroughly investigated. The vascular apparatus is sufficiently deve- 
loped in these Echinoderms, and appears to have for its centre an 
elongated canal with muscular walls, which may with some justice be 
honoured with the name of heart. A little ring surrounding the 
cesophagus, and from which issue certain delicate white cords, which 
are prolonged into the furrows of the arms, presents us with all that 
can be designated a nervous system in the star-fishes. Among organs 
of sense we may, perhaps, mention, as being sensible of touch, the 
tentacular ambulacral feet. The eyes are considered to be certain 
bright red points which are situated at the extremity of the arms 
almost on their under surface—a most singular position for the organs 
of sight. The eyes must, however, be very imperfect, for they possess 
no crystalline lens. Ehrenberg insists upon the existence of eyes 
in some species, attributing the function to those red spots, however ; 
while Rymer Jones attributes the indications of sight-seeing sometimes 
observed to an extremely delicate sense of touch in the star-fishes, 
Professor Edward Forbes, while he admits the existence of ganglions 
in the nervous system to be extremely doubtful, seems, by the frequent 
use of the terms eyes and eyelids, to admit that the specks in question 
are visual organs ; the weight of authority inclines therefore to Ehren- 
berg’s view, that if not eyes in the strict sense of the term, they serve the 
purposes of vision, modified and adapted to the wants of the animal. 
The star-fishes have distinct sexes, with individual differences ; 
their eggs, which are round and reddish, undergo curious phases of 
development. They produce little worm-like creatures, covered 
with vibratile cilia, like the Infusoria, which swim about with great 
vivacity ; these little creatures are subject to considerable changes. 
_In the year 1835 M. Sars described, under the name of Szpznnaria 
asterigera, an enigmatical animal resembling a polyp from the arms 
at one extremity of the body, while the other terminated in a tail, 
furnished with two fins ; but it was chiefly remarkable as having an 
Asterias attached to the extremity which carried the arm. He 
expressed an opinion, which was soon placed beyond any doubt, that 
this dip¢nnaria was an Asterias in its course of development. The egg 
becomes a sort of infusorium, the infusorium becomes a &spinnaria, 
and this produces the Asterias. In short, the Bipinnaria does not 
become an Asterias by any metamorphosis analogous to that so well 
known amongst insects—the butterfly, for example—but becomes, so 
to speak, the foster-mother or nurse to the Bipinnaria. The larval 
form is large, and it is at the cost of a very small internal rudiment 
of this larval form that the Asterias is developed: the Asterias robs 
the larval form of its stomach and intestines, and turns it into a 
