EA 
1879.] Zoölogy. 4I 
ture of the Nazidacee. He especially described the ns Eas 
of leaves in the genus He/ophila. In this marine tropical phnzo- 
gam, the stem is a creeping jointed rhizoma; at each joint occurs 
a pair of sheafing scale leaves. No foliage leaves occur on the 
main axis. In the axil of one scale leaf of each pair arises eccen- 
trically a lateral secondary shoot, which is a jointed rhizoma like 
the parent, and the first pair of leaves upon it is a pair of foliage 
leaves, the succeeding leaves on this axis are all scale leaves. 
From these secondary axes tertiary ones arise, which again re- 
peat the process. Thus the foliage leaves in these plants only oc- 
cur as the first pair of leaves on the lateral shoots. This is prob- 
ably unique in the vegetable kingdom. The pee See of the 
parts of the male and female flowers were also pointed o 
The Bulletin of the Torrey Botanical Club for October (which 
was late in coming) contains several notes by Messrs. Eaton, 
Underwood and Gilbert, on the ferns of the United States. 
In the Botanical Gazette for November, Fendler’s Ferns of Trini- 
dad are noticed by Prof. Eaton. The leaves of Darlingtonia cali- 
puttin and their two secretions are described by Mrs. R. M. 
ustin. 
ZOOLOGY. ! 
ON THE ORIGIN OF BILATERAL SYMMETRY AND THE NUMEROUS. 
SEGMENTS OF THE SoFT Rays oF FIsHEs.—As is well known, the 
soft fin-rays of Acanthopterous fishes and all or most of the fin- 
rays of Malacopterygians, are composed of two bilaterally sym- 
metrical ossified and more or less completely segmented halves, 
semicircular in section, each having a groove on its inner face to 
receive between them a cartilaginous medulla. Their embryo- 
logical history shows that the process of ossification is progressive 
from without inwards, or in the language of recent authorities it 
may be styled ectosteal. 
Viewed in a non-teleological, or in the light of what seem to 
be the probable mechanical (dynamical) differentiating causes, their 
origin becomes extremely simple. No type of vertebrate limb 
has such exceedingly short and numerous segments in relation to 
its total length. In extreme contrast with them we may place the 
digital wing-elements of the Chiroptera and Pterosauria, and of | 
these it may be said no vertebrate types exhibit such excessive 
elongation of the digital elements in proportion to their aggre- _ : 
gate length. Contrasting their habitual modes of use in relation 
to their surroundings, we find the media, water and air, in which 
the two, respectively fins and wings, are used differ as widely in 
respect to density. That such difference in structure should ac- 
company such widely differing conditions would seem to be 
caused by those conditions. Then, like those types which peram- 
bulate over approximate planes, there are no definite points of im- 
The departments of Ornithology and Mammalogy are conducted by Dr. ELLIOTT 
S. A. : 
Cou esc U. 
,. 
