142 Transactions of the Royal Microscojpical Society. 
there during the summer. Bucephalus was developed in great 
numbers a few days after its first appearance, and exhibited a beau- 
tiful sight of transparent creatures flying like eagles through the 
water, the wing-like appendages spreading out to an enormous 
length, and constantly in motion, with a general upward tendency. 
They never attached themselves to any object, but always swam 
freely, and were neither seen to feed upon other creatures, or to be 
the objects of attack. The top of the central organ exhibited, 
under the microscope, a small slit or sucker, and a ventral contrac- 
tile sucker. The slightest pressure bursts the two bags, as well as 
the side appendages ; while the central organ, thus set free, retains 
an independent vitality for a considerable time, and preserves its 
structure, although the other parts resolve themselves into a shape- 
less mass of globules. 
" The animal, as a whole, is extremely brittle, and often breaks 
in pieces, the lateral organs usually coming off. When removed 
with a dipping tube, and placed in a small bottle of water, a little 
shaking easily breaks them up, unless the bottle is quite full. 
" They are so transparent that small objects, such as the cilia of 
paramecia or vorticella, can be readily seen through them. 
" The side appendages are capable of wonderful extension, being 
often thrown out to four or five times their normal length, with a 
quick active motion quite unlike the deliberation with which the 
hydra moves its tentacles. 
"During four months no other change than those mentioned 
was observed in the form of these creatures, and they all vanished 
on the setting in of cold weather." 
Mr. Badcock showed these creatures to several well-known 
naturalists, to many of whom it was quite new ; and no one of those 
who recognized it as Bucephalus jpolymorjphus was well acquainted 
with it, which shows that it has not been sufficiently noticed. 
From a cursory view of the animal, it was evident that many 
specimens would be required to make out its internal structure. 
When not compressed, no internal organs were visible during the 
short time it was exhibited to the Society, and, as Mr. Badcock 
reports, pressure easily destroys it. 
The rough sketches appended by Mr. Badcock to his note leave 
little doubt that the creature is the Bucephalus polymorphus of Yon 
Baer, described by that author in the ' Nova Acta ' of the Leopold- 
Caroline Academy of Bonn, in the vol. for 1826, p. 570, from which 
Figs. 1 to 5, PI. XCYIII. are taken. Fig. 1 is like the specimen 
shown to this Society, except that the latter did not exhibit the same 
obvious distinction between the integuments of the lateral append- 
ages and their contents ; on the contrary, they seemed hollow, and 
without solid contents. Von Baer states in his paper that he found 
the animals in mussels, and in 1825 was able to trace their develop- 
