NATURAL HISTORY MISCELLANY. 311 
and P. vetus), and two rails ( Telmatornis priscus and T. affinis). Besides 
these there are descriptions of four species of Tertiary birds, the first 
that have been regularly described from that formation in this country. 
These are sl to be more closely allied to existing species than those of 
the Cretaceou They are — Conradi, Catarractes antiquus, Grus 
Haydeni, and in Idahen 
Though the discovery of man remarkable bird, the Archeopteryx, in 
the Jurassic beds, led naturalists to suppose that Cretaceous forms 
would be eventually discovered, to Professor eia energy we owe 
the fulfilment of these anticipations. 
NATURAL HISTORY MISCELLANY. 
BOTANY. 
HIBERNATION OF DUCK-WEED. — It has long been known that some spe- 
cies of Lemna, or duck-weed, produce, at the approach of winter, leaves 
of a different character to those formed in the spring, which fall to the 
th nd or i 
winter. A series of more accurate observations on this point is recorded 
by M. Van Hoven in the ** Bulletin de la Société Royale de Botanique de 
Belgique." The species of Lemna indigenous to Belgium are the same as 
those found in this country; of these M. Van Hoven finds that two only, 
the L. polyrrhiza and gibba, produce leaves of a different form in winter; 
while with the three other species, L. minor, trisulca, and arrhiza, the 
ena leaves live through the winter, remaining on the surface. In 
oe these winter-leaves first make their appearance in August or 
Septem They are much smaller than the. ordinary leaves, reniform 
or Musici elliptieal, olive-brown on both sides, and not gibbous be- 
neath; their roots are exceedingly minute, and at first hidden within the 
first frost. At the e ordinary gran of the Mu AC of vegetation, a small 
bubble of oxygen appears on the upper surface of these submerged: 
leaves, which carries fpe to the surface, from which they again descend 
[n ertai t. m Lemna gibb 
x 
water, differing in shape, size, and structure from those developed during 
summer. — Quarterly Journal of Science. 
