STRETHILL WRIGHT, ON THE EOLID#. 53 
* Dr. Strethill Wright, after describing the anatomy of the 
respiratory, digestive, and hepatic organs in the Eolide, 
stated that in his memoir on Hydractinia echinata, read 
before the society, November 26th, 1856, he had written— 
Hydractinia is infested by a small species of Holis (Kolis 
nana), which peels off the polypary with its rasp-like tongue, 
and devours it—possessed, I suppose, of some potent magic, 
which renders all the formidable armament of its prey of no 
avail. Now, each of the dorsal papillee of the Eolidze contains 
at its extremity a small ovate vesicle, communicating, through 
the biliary sac, withthe digestive system, and opening externally 
by a minute aperture at the end of the papillee. This vesicle is 
found crowded with compact masses of thread-cells, which masses 
in Eolis nana, consist of aggregations of small and large thread- 
cells, identical in size and shape with those of Hydractinia— 
on which this Eolis preys—not contained in capsules, but 
cemented together by mucus. When we consider that each 
of the vesicles is in indirect communication with the stomach, 
I think we may, without presumption, suggest that the 
masses of thread-cells found in Eolis nana are quasi fecal 
collections of the thread-cells of Hydractinia, which, protected 
by their strong coats, have escaped the digestive process. In 
corroboration of this view, I may mention that the Eolis 
papillosa, as figured in the work of Alder and Hancock, have 
a perfect resemblance to those found in the Actinias, which 
last animals furnish an Abyssinian repast to these carnivorous 
mollusea.” Dr. Wright afterwards found that, as to the 
above idea, he had been anticipated by his friend, Mr. Gosse, 
who, in his ‘Tenby,’ after noticmg the existence of the 
thread-cells in the papilla, remarked—“ The inquiry I suggest 
would be, how far the presence of thread-cells might be 
connected with the diet of the mollusc? And whether, 
seeing the forms of the missile threads vary im different genera 
of zoophytes, the forms of the corresponding orgaus im the 
papille of the Eolides would vary if the latter were fed ex- 
clusively first on one and then on another genus of the former.” 
He afterwards found that Mr. Huxley had also doubted, pre- 
viously to Mr. Gosse and himself, whether the thread-cells of 
the Eolide were not adventitious. Here were three inde- 
pendent observers to whom the idea had suggested itself: 
Mr. Huxley had first hinted it; Mr. Gosse suggested it and 
how it might be found to be true; Dr. Strethill Wright also 
had suggested it, and given two instances in corroboration of 
his opinion, and then he proceeded to detail observations 
which would, he hoped, entitle it to be enrolled as a proved 
fact in the records of science. Ist. A specimen of Eolis nana 
