1885.] Zoölogy, 311 
usual, and the same is true of the water-vascular system. Of 
especial interest are tactile papilla, which beset the surface, and 
which obviously enable the sporocyst to find the definitive host 
for its contained larva. These papillae are somewhat more com- 
plicated than the similar structures described by Fischer from the 
neighborhood of the cirrus-pouch of Opisthotrema cochleare (Zeit. 
wiss. Zool. XL, 12). Ina future paper I propose to give a full 
account of the structure of the sporocyst and its contained larva. 
It would be premature to attach any specific name to the Dis- 
tome, as it may turn out to be a well-known form, but I am at 
present unable to offer any suggestion as to its “whence” or 
“whither.” I examined the mollusks in the aquarium for other 
specimens in vain, and, in the hope of obtaining others for infec- 
tion experiments, hardened and sectioned the only one I had se- 
cured, 
Professor Leuckart, to whom I communicated the substance of 
the above, writes: “ Your observation is certainly calculated to 
astonish helminthologists. I doubt whether the creature is really 
free-living, but believe that, in place of the Cercaria, it represents 
only the swarm-phase of the parasite. An entirely free-living 
sporocyst, without intestine, would hardly find the conditions 
necessary for a complete existence. It probably lives parasiti- 
cally within a mollusk, and wanders out after development of the 
contained larva, in order to seek a suitable host for the latter. 
Perhaps it may attach itself to the host by the flat lobes of the 
forked tail, and then discharge the larva imprisoned within it.”— 
R. Ramsay Wright, University College, Toronto, Fan. 12, 1885. 
STRUCTURE oF EcuHINopERMS.—C. F. Jickeli has a preliminary 
note in which he states that he has made experiments confirma- 
tory of the doctrine of Carpenter as to the nervous system of 
Comatula. He finds that a -single arm gives no response when 
the ambulacral groove is touched with a needle or stimulated by 
an electric current, but that the moment the needle touches the 
point at which the axial cord lies the arm is strongly flexed, and 
the pinnulæ more actively. A single cirrus when stimulated 
appears to be thrown into a tetanic condition. Many of the 
author’s experiments are in exact agreement with those of Car- 
penter. After the removal of the visceral mass irritation of the 
capsule produces a synchronous contraction of all the arms. Ifa 
few drops of osmic or acetic acid are put in the water, the 
i njured animal. 
bY : 
observations of P. H. Carpenter that nerve-branches pass into 
the dorsal and the ventral muscles is confirmed. A series of sec- 
tions shows that the ambulacral nerve diminishes in extent as it 
approaches the intestine, and finally disappears. Attention is 
