42 J Veil. 
ECHINODERMATA. 
inheerens , and Vortlcella amphiuree , n. sp., commensal on Amphiura 
squamata. Dinoflagellata : Procentrum micans , Ehrenb., from the gut 
of Anteclon rosacea and ? Procentrum , sp., in the ambulacral groove of 
Echinasler sepositus. Sporozoa : Syncystis synaptce , Ray Lank., from 
coelome of Synapta inheerens ; Syncystis miilleri , Giard, sp., from coelome 
of Synapta digitata ; Syncystis holothurice , A. Schn., from coelome of 
Jlolothuria tubulosa and Lithocystis schneuleri , Giard, from the coelome of 
Echinocardium cordatum. 
Demoor & Chapeaux have studied the physiology of the nervous 
system of Asterias nibens , and arrive at the following conclusions : — 
a. Movements of the arms and re-assumption of the normal positiou. 
The two nervous systems, condensed and diffuse, have each a distinct and 
absolutely autonomous physiological role. The co-ordinated movements 
which bring about the re-assumption of the normal position of the animal 
are reflexes, depending upon the condensed nervous system. The inter- 
vention of the centres united round the mouth increases the rapidity of 
the phenomenon. 
b. Autotomy, as a motor reaction, is a reflex which has a centre in the 
nerve ganglion of the arm. The intensity of the phenomenon is a f unc- 
tion of the number of ganglia working co-ordinately. 
C. Reactions of the ambulacral tentacles. Retraction of the tentacles 
is the result of a simple reflex, the irradiation of which, in the nervous 
system, is the more rapid the nearer it takes place to the peribuccal cord. 
Thus the perioesophageal nerve centres have an influence on this pheno- 
menon. Extension of the tentacles is a reflex of the second order, con- 
sequent on an irritation diffusing itself strongly in the same nervous 
apparatus. This irritation is determined by the strong stimulation of 
some point of the condensed nervous system, which brings about locally 
the primary reflex, i.e., retraction, or by a stimulation of tho diifuso 
nervous system transmitted to the ventral nervous system. The pheno- 
menon of extension of the tentacles does not necessarily depend on the 
functions of the ganglia, although the influence of the ganglia acts notably 
on the propagation of this reflex, which is always centrifugal. The 
reactional capacity of the normal A sterias depends on the integrity of the 
diffuse nervous system. This apparatus gives the condensed nervous 
system the power to react, and it is tho first cause of tho automotricity 
which constitutes the principal function of the condensed nervous 
system. 
d. Movements of the tubules and pedicillariae are independent of the 
condensed nervous system, and depend exclusively on the diffuse nervous 
system in the deeper layer of the epithelium of the skin. Some bodies 
produce extension of the tubules, others retraction, others diminish, and 
others again increase the reactional power of the tubules, while others 
finally do not affect it. 
E. Movements of isolated dorsal integuments. They try to right 
themselves when put in an abnormal position, the cause of which appears 
to be the tonicity of the integuments. 
