1890.] Zoology. 187 
origin of the secretion which produces these lids is utterly unknown, 
nor is it known whether it is produced by male or female. 
New Glands in the Hemipterous Embryo.—lIt is well known 
that in the insect embryo traces of rudimentary appendages occur on 
the abdominal segments, but the histology goes to show that these 
evanescent structures on the first abdominal segment have lost their 
ambulatory function and have taken on another. One series of in- 
vestigators believe that they are gills, the other as sense organs or 
glands. Mr. W. M. Wheeler has studied homologous structures in 
Cicada and Nepa, and finds (Zool. Anz., 317) that in these forms there 
is no protruding appendage, but in its place a swollen ectodermal 
tch composed of greatly elongate epithelial cells, flat on the free 
surface and extending itself into the interior of the y: oceed- 
ing from these cells was found a secretion which varied in character 
(in hardened specimens) in the two forms studied. In Cicada it 
formed a vacuolated transparent mass ; in Nepa it formed a brush-like 
mass of elongate threads, apparently a thread to each secreting cell. 
There was apparently no connection with the nervous system, so that 
these organs in the Hemiptera must be regarded as glandular. Con- 
cerning the functions of these and other similar glands, it is difficult 
to say, but it is possible that they may fall among the category of 
silk-glands, and play a part in making these forms nauseous mouth- 
fuls for insectivorous animals. 
Abdominal Appendages of Lepismida.—Oudeman shows 
that there is a regular succession in the appearance of the ventral ab- 
dominal appendages in the Thysanurous form, Zhermophila furnorum. 
In the smallest forms only the pair belonging to the ninth segment are 
present ; increase in size brings the eighth pair, while only the full 
grown individuals have appendages on seventh, eighth, and ninth seg- 
ments. Oudeman thinks this adverse to the view that these are rudi- 
mentary appendages homodynamous with the others. 
The Segmentation of the Vertebrate Brain.— Mr. C. F. 
W. McClure attacks (Zool. Anz. 314) this oft-studied problem from 
another standpoint. He finds, in studying Amblystoma, Anolis, and 
the chick, that there is an evident segmentation of the nervous centre, 
it being divided, in an early stage, into segments or neuromeres, which 
alternate with the mesodermic somites. This segmentation extends 
into the cranial region, and embraces the whole of the brain, the fore- 
brain consisting of two (possibly a portion of a third), the mid-brain 
