EOSACEUS, LINCK (COMATULA EOSACEA OF LAMAECK). 
527 
as soon as the interior of the cup can be examined after its expansion, the number of 
extensile tentacles has reached fifteen ; but from the one or two instances in which the 
ten additional tentacles have been absent, there can be no doubt that they are developed 
somewhat later than the five already described. They arise in five pairs, one tentacle 
on either side of and slightly within the base of each of the azygous tentacles, which 
they resemble closely in character. They commence as minute csecal diverticula from 
the canal which passes through the enlarged base of the azygous tentacle, and become 
rapidly developed into tubular prolongations. At this stage (Plate XXVI. fig. 1), 
when the cup is open, the fifteen tentacles are usually fully extended, curving over the 
edge of the cup in the angles between the oral lobes, in threes, the azygous tentacle 
somewhat longer in the centre, and one of the paired tentacles on either side. 
Interradially, opposite each of the oral lobes, there is a pair of short tubular tentacles, 
their cavities likewise continuous with that of the oral vascular ring. These tentacles 
appear simultaneously with the five azygous extensile tentacles, immediately on the 
expansion of the cup. They are flexible, but not extensile, slightly club-shaped towards 
the distal extremity, which is fringed on either side by a single row of short conical 
tubercles. The base of these tentacles is involved in the contractile sarcode ring sur- 
rounding the mouth. When the disk is fully expanded they lie in pairs up against 
the inner surface of the oral lobes. They are frequently, however, gathered inwards 
together, or singly curving over the mouth. They form part of a very characteristic 
system of “ non-extensile tentacles,” which afterwards fringe the radial and brachial 
grooves. At this stage, then, the oral ring usually gives off twenty-five tentacular 
appendages, of which fifteen are radial and extensile, and ten are interradial and non- 
extensile. 
Imbedded in the sarcode at the base of each of the azygous tentacles, a peculiar 
glandular body is very early developed. At first it consists of a minute vesicle con- 
taining a transparent fluid. The vesicle gradually increases in size till it attains a dia- 
meter of about 0'08 millim. in diameter. Its contents become granular, and at length 
it has the appearance of a large cell with a special wall, included in a capsule formed 
of a firm sarcode-layer, from which the cell can be turned out unbroken. 
The cell contains a number of large, irregularly-formed, transparent, slightly granular 
masses, which are set free by the rupture of the cell-wall. These masses are quite 
colourless. They are coloured by carmine more deeply than the general substance 
of the body, and after death they become immediately strongly coloured by the red 
pigment set free from the perisom. I have been utterly unable to determine the 
function of these bodies. They are produced in great numbers, during the growth of 
the pentacrinoid, along the edges of the radial and brachial grooves, and are permanent 
in the mature Antedon. The only speculation which seems to me at all feasible, a specu- 
lation which derives some support from their peculiar affinity for colouring matter, is 
that they are glands connected with the secretion of calcareous solution for the develop- 
ment and nutrition of the skeleton, analogous to the calcareous glands so constantly met 
