142 REPORT—1840. 
Cydippe is cut off, it has of itself no power of motion, but if the smallest 
portion of the substance of its base remain attached, it moves with 
great vivacity. Hence the observers conclude that the ciliary motion 
is effected by undulatory movements of this peculiar tissue, which 
explanation will also account for the rotatory appearance of the circles 
of ciliz on certain animalcules, and on a remarkable apparatus which 
they have discovered in the breathing sacs of the Eehiwrus, a vermi- 
grade Echinodermatous animal, allied to the Sipunculus. They reject 
altogether the explanation of the ciliary motions given by Professor 
Ehrenberg, Dr. Grant, and M. Raspail. From observations made on 
the circulating system of the Beroidez, they are led to conclude that 
the usual definition of that tribe, as acalephous animals having two 
openings to their intestinal canal, the one anterior and the other pos- 
terior, is incorrect. They believe the supposed anus to be imperforate, 
and a great portion of the supposed intestinal canal to belong to the 
circulating system. 
The tongue-shaped organ which Mr. Forbes formerly described as 
existing in the stomachs of many of the Cydippes, has proved to be a 
remarkable parasite trematoid worm, fixing itself by means of four 
- suckers or mouths to the walls of the stomach, and of the vessels of 
the Cydippe, often interrupting the circulation of its fluids. For this 
strange parasite Mr. Forbes has constituted a new genus, and desig- 
nated it Yetrastoma Playfairei, in honour of Major Playfair of St. 
Andrews, who first drew attention to its parasitic nature. The authors 
summed up their paper by stating the results:—lst. That ciliary 
motion was effected in the Ciliograda by means of a granular tissue, 
similar to that forming the bodies of the Hydroide and the iower 
Entozoa, on which the ciliz are placed: 2nd. That the Ciliograda are 
not Acalepha, having two openings to their digestive canal (as has 
hitherto been stated), but similar in structure to the other Medusz : 
and 3rd. The discovery of parasites infesting the Acalepha. 
- 
On Meduse. By R. Patterson, F.L.S. 
After briefly noticing some of the specific distinctions of two species 
of Medusee common on the Irish coast (Cyanea Lamarchii and Aurelia 
- aurita), Mr. Patterson stated, that his object in bringing forward the 
present communication was, principally to direct the attention of the 
members to the Acalepha of the British shores, a portion of our Fauna 
hitherto uninvestigated. With this view he described at some length 
their habits and appearance. He next proceeded to detail some of 
their peculiarities of organization, especially the difference observable 
in their filamentary appendages, and the varying number of the mouths 
and arms. Our ignorance of their physiology was exemplified by a 
series of questions relative to the organs of sensation which they pos- 
sess, and the origin and uses of their luminosity, their stinging powers, 
their means of defence and propagation, their length of life, and their 
peculiar parasites. 
