DR. WILSON ON THE NERVOUS SYSTEM OF THE ASTERID.E. 119 
The ganglion and interambulacral nerve-cords are well-developed. The relation they 
bear to the skeleton will at once be understood by referring to fig. 8, Plate XII. The 
perioral spines are only four in number ; and the masses (b b) bearing them support also 
the vertebral plates (a a) directly, there being no intermediate piece. The integument is 
firmly connected to the fibrous tissue beneath, as far outwards as the interambulacral 
cords. These latter have a close relation to the vascular perioral ring conuected to the 
heart. 
Microscopically, " the ganglions are a collection of nerve-cells clustered together and 
forming a union, as it were, between the interganglionic and ambulacral nerve-cords*. 
Pilaments pass outwards, and also to the different cords in connexion with it. Some may 
likewise be detected passing inwards to the perioral space." Other "small filaments 
diverge outwards, very soon passing backwards into the interior of the animal, through 
small foramina in the calcareous plates." t 
The interambulacral nerve-cords have each " a series of cells arranged pretty nearly in 
a line, and sending filaments longitudinally as well as inwards and outwards." 
On the Reproduction of lost Bays. 
Before concluding, I would offer, though still imperfect, some few observations, made 
at different times, upon the reproduction of the lost rays in TJraster nibens. The speci- 
mens I examined were gathered close to Newhaven Pier, and were therefore principally 
those which had survived the rough handling and ill-treatment of the fishermen. The} 
can be procured of all shapes, from four- to one-rayed, and with the reproduced portions 
in all stages of development. These stages I have attempted to give in a series of five 
drawings X . 
After a ray has been torn off or otherwise destroyed, the healing process commences 
by the disintegration and subsequent rejection of those portions of the integument and 
skeleton which have undergone fatal laceration. While this is going on, the dorsal skin 
with its calcareous network curves downwards and slightly inwards upon itself, until it 
reaches the vertebral arch. Union then begins in the mesial line by the dorsal flap send- 
ing inwards a small pointed process, which becomes connected to the integument and the 
fibrous tissue of the vertebral arch. The lateral portions of the flap next cicatrize, with 
the skin covering the ambulacral aspect of the vertebral plates. Their broad surfaces, 
however, remain free,— a distinct cul-de-sac existing between them and the dorsal integu- 
ment, very well seen in a longitudinal section 
A prolongation from the ambulacral nerve-cord is soon observed, covered, of course, by 
the skin, and supported on its dorsum by a soft tubercle which is developed simultaneously 
*ith it from the dorsal flap. This is followed by the deposit of pigment; but whether 
it is a perfect eye at this stage, I am still uncertain. It soon, however, presents the cha- 
racteristic cones, each with the smaU clear spot at its base. The subsequent stages are 
the further elongation of the cord and of the dorsal integument, with the development oi 
the vertebral plates and suckers. 
* Plate XV. fig. 7. 
t 
X 
10-14. 
