THE ELEXTBLE CREEPERS. 489 
present, "but in others there is a very small one, with two 
excessively minute toes. 
Of the habits of the animals of this order, perhaps the most 
interesting examples are those afforded by two species of 
Notommata — N. petromyzon and N. parasita, which live — the 
former occasionally, the latter habitually — in the majestic rolling 
spheres which bear the name of Volvox globator . In an inter- 
esting paper by the Editor of this Review, the appearance and 
the salient points of the history of this remarkable organism, 
once considered an indubitable compound animal, now by most 
naturalists referred to the vegetable kingdom, — are well given.* 
Within the beautiful green spheres of the I T olvox,N .parasita may 
be frequently seen comfortably lodged, whence Ehrenberg gave 
it the appropriate designation of “ the Pirate On examining 
several Volvoces, even with a pocket lens, we may frequently 
detect such as are thus tenanted by their containing one or 
more spots, differing from the young clusters in form and 
colour. Each of these spots is found to be a Notommata, 
snugly ensconced within the globe, in the spacious area of 
which it lives at ease, and swims to and fro like a gold-fish in 
a glass vase. We see it for the most part, however, clinging 
to the inner surface of the circumference, engaged in devouring 
the green monads with which its gelatinous expanse is studded, 
or else eating away the embryo clusters. The action of the 
protruded jaws of the Notommata, as it eagerly nibbles away 
at the monads, is very energetic ; but its progress is not com- 
mensurate with its vehemence. I have not been able to see 
one actually detached and swallowed. Frequently two or more 
Notommatce are found in the same Volvox, and 1 have seen as 
many as four, with an egg besides. They do not interfere 
with each other, but each pursues his own avocation. 
It is chiefly the smaller Volvoces that contain the parasite, 
especially those which have the embryos very immature. I 
have not seen any loose in a large Volvox ; but in embryos 
almost grown, and nearly ready for escape, I have several 
times seen a Notommata . If we wonder at this Rotiferon 
obtaining access to the interior of the sphere, we wonder still 
more at seeing even the young spheres, while yet within the 
mother sphere, thus tenanted, especially as the circumference 
both of mother and daughter appears unbroken. On careful 
examination, however, the parent Volvox shows places where 
the monads are interrupted; and I have thought that I could 
discover, in each case of a tenanted embryo, that its circum- 
ference had a ragged point. 
The Volvox does not appear to suffer from the depredations 
* “ Popular Science Review,” vol. i. p. 57. 
