joutSmISTTs^^^^ progress of microscopical science. 189 
new species are exactly the same as those of Limnoria terebrans, with 
which it is generally confounded. This co-existence has led to many 
mistakes. While both species are, he says, very common, it is to 
be borne in mind that the L. terebrans is much commoner than the 
other. The new one, like the old, swims with great facility ; it turns 
on its back, which then forms a sort of keel, and, using its thoracic 
feet as oars, it employs its abdominal false limbs as a rudder. When 
it walks it moves much more slowly, and when touched it rolls itself 
into a ball, like certain other species. It attacks nearly all submerged 
woods, but it especially favours young woods and the French pine. — 
Annates des Sciences, t. X., 1868. 
Researches on the Wing of the Orthoptera is the title of a paper in 
the above journal, by M. H. de Saussure. The details of the peculiar 
mode of plication of the wing are fully entered into. 
The Development of Oblique Leaves is the subject of a paper by Dr. 
Wilder in the last volume of the ' Proceedings of the Boston Society 
of Natural History.' The author thinks that the obliquity of leaves 
is not to be explained by reference to external operations, but is the 
expression of certain definite internal qualities. 
The ThalassicollidcB. — Dr. G. 0. Wallich has a very interesting 
paper on this group in the ' Annals of Natural History ' for February. 
One of the points discussed is the relation of Thalassicolla nucleata to 
Noctiluca. It would be impossible to abstract this paper. 
The Gonidia of Lichens changing into Zoospores. — This is a paper 
by MM. Famintzen and Boranetzky, and is translated in the 'Annals* 
for February by the Eev. W. A. Leighton. The authors give experi- 
ments to prove this singular transformation, and they tabulate the 
following propositions : — 1. Not only AlgsD and Fungi, but Lichens 
are provided with zoospores. 2. Zoospores have been found in three 
very different genera of Lichens, viz, Physcia, Cladonia, and Evernia ; 
and as these genera were selected undesignedly, it is probable that 
zoospores exist in all other lichens provided with chlorophyll. 3. We 
have demonstrated the existence of free gonidia with the unicellu- 
lar alga, Cystococcus of Nageli ; consequently this is not a distinct 
genus, but only a phase of development of a lichen. 4. The culture 
of the free gonidia of the three species above, led us to expect that 
other lichens would present forms corresponding with rudimentary 
Algae, and our researches proved this. Vertical sections of the thalli 
of Feltigera and Gollema cultivated on moist earth showed the fila- 
ments in disintegration, the augmentation in size of the gonidia, and 
their transformation into glomerules composed of spherical cells. 
The gonimic cellule of Peltigera and Collema continued to live when 
separated from the thallus. Those of Peltigera were identical with an 
alga called P oly coccus ; those of Collema produced organisms similar 
to Nostoc. Consequently these three genera of AlgsB, hitherto re- 
garded as different and distinct, are in reality only the gonidia of 
lichens in a state of development when separated from the thalli 
which produced them. 
VOL I. p 
