322 
REPORT ON ZOOLOGY, MDCCCXLII : 
(I’lnstit., 1841, p. 398.; Ann. d. Sc. Nat. t. 17, 1842, p. 22; and 
Fror. N. Notiz. Bd. 21, 1842, p. 165.) : — Corpore molli, vermiformi, hie 
et illic mode turgido, mode constricto et transversim plicate ; cuti roseola, 
hyalina, adhaerente ; vittis quinque fibrosis, opacis, albis, longitudi- 
nalibus instructa : ore plana, duodecim tentaculis pinnatifidis circumdato ; 
ano rotundo, nudo, terminal!. This animal prefers the sea-slime, and 
feeds on the sand, with which its whole intestine is stuffed. It very 
quickly separates the hinder part of its long vermiform body, either 
voluntarily or on touching it ; the fragments of the animal thus thrown 
off move about for three or four days. The animal itself changes its 
position by vermiform windings of its body, making use of its tentacles 
for that purpose, which are in constant motion, and are at the same 
time employed as grasping-organs. Although this Synapta shows sen- 
sibility to a very strong admission of light, yet it does not appear to 
possess any definite organ of sight ; it has also no perception of sound. 
Its cuticular covering is composed of a tender epidermis and a corium, 
which is slightly rose-coloured, by a transparent granulated substance. 
The upper surface of the body is not smooth, but covered by a number 
of oval elevations like raspberries ; these bear remarkable anchor-shaped 
angular hooks, which are toothed on the convex side of their two barbs, 
and have a small arched dentated dilatation at the upper end of the 
stalk opposite the barbs. The barbs or anchor-shaped bodies, which 
are about the length of 1^0 mill., are fastened by the upper dentated 
end of the stalk, in an oblique direction, to a small perforated shield. 
These parts, the anchor and shield, become dissolved with effervescence 
in acids, while they are not affected by caustic potass. The other 
elevations which do not bear anchors are covered with small spherical 
and oval bodies, some of which are striped transversely. These bodies 
can protrude from their interior a filiform body of mill, in length ; 
they are not affected by acids, but are dissolved by kali causticum. 
Quatrefages compares these little bodies with the nettle organs of the 
Actiniae, and believes that the anchors do not exclusively, as Eschscholtz 
supposes, cause the bur-like appendages and the urtication of the 
Synapta, but that the last described bodies, principally as in the 
Actinics, work as stinging organs. The anus is opposite the mouth, 
at the end of the hinder part of the body. The five feathered tentacles 
surrounding the mouth, have a tenderer cuticular covering than the rest 
of the body, and bear neither anchor nor shield, nor stinging organ, 
but are furnished with two rows of acetabula on their inner surface, 
which are very useful for taking the food and in creeping forward. 
The tentacles, in which the circulation of the blood is maintained in a 
lively manner by the vibratile epithelium, also probably serve as organs 
of respiration ; but at the same time a contrivance by which the Synapta 
constantly take up water into the cavity of the body, and again 
366 
can 
