8 
Transactions of the Society. 
mistake, quite as bad as this, that Sckmarda is supposed to have 
made; and that too, in the case of an animal, of which he had 
numerous examples, and whose true form could be easily seen under 
a low power. It is probable then that Hexarthra exists, and that 
the Rotifer a, in this species, make a still nearer approach to the 
Nauplius larva of the Arthropoda. Of course, if the Rotifera do run 
up to the Arthropoda through Pedalion and Hexarthra , there must 
be other forms lying between the outposts of the two classes, with 
which we are unacquainted, and which it is possible that we may yet 
discover. Nor do 1 think that I am too sanguine in supposing, that 
some of these connecting links, on either side of Pedalion , may yet 
be extant. For the Rotifera, owing apparently to their extraordinary 
power of adapting themselves to varying circumstances, contain 
more than one long series of forms connecting species that, at first 
sight, seem hopelessly wide apart. Place Trochosphsera , Stephano- 
ceros, and Actinurus side by side ; could there be a more discrepant 
trio ? And yet we possess many intermediate forms which link the 
three together. 
The persistence of such links gives us, I think, good ground for 
hoping that the missing forms, between Pedalion and the other 
Rotifera , may yet exist ; and (whatever may be thought about 
Hexarthra) possibly some too between Pedalion and the Arthropoda. 
At any rate it is worth while to try to find them ; and, if so, where 
can we search with the best prospect of success ? It is hardly likely 
that their natural homes are in Europe, or the United States ; for, 
if they were, they could hardly have escaped the sharp eyes there, 
that are ever prying for novelties ; it is in the tropical and semi- 
tropical countries that we must conduct our search. Their lakes, 
tanks, flooded rice-fields, swamps, and irrigation-canals — all swelter- 
ing under the sun, and abounding in minute vegetation — have 
surely a wealth of new microscopic creatures yet in store for us. I 
only know of four observers, who have had the good fortune to 
explore these almost virgin fields of research, and each has found 
at least one prize. Dr. Semper discovered the female of Trocho- 
sphsera sequatorialis in the flooded rice-fields of Manila ; Dr. Schmarda 
Hexarthra , in the irrigation canals of Egypt; Surgeon Gunson 
Thorpe, B.N., the male of Trochosphsera sequatorialis , near Brisbane ; 
and Mr. Whitelegge, at Sydney, that curious social Melicertan 
Lacinularia pedunculata ; which, anchored by its long thread of 
intertwined stems to the leaves of Myriophyllum, floats on the surface 
of shallow pools, “ like acacia blossoms that have fallen into the water 
from the trees above.” 
Pedalion, too, which has given rise to this question, itself would 
seem to suggest the same answer. F or it is a very rare creature, and 
does not thrive in our ponds, dying out after the first or second year. 
The only spot where it seems more at home is in the warm water 
lily-tank in the Duke of Westminster’s conservatory at Eaton. This 
