ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 341 
contribution which his paper makes is the detailed description of the 
larvas and nymphs. 
Development of Central Nervous System of Blatta germani' .* — 
Mr. N. Cholodkovsky has a preliminary notice of his observations on this 
subject. The nerve-groove is not continuous at first, but arises gradually 
by the union of separate small pits, which appear at the base of tho 
developing extremities. It is continued forwards into two tentacular 
grooves. The supra- oesophageal ganglion arises from three pairs of rudi- 
ments, of which the first pair is pre-oral, the second lies on either side of 
the mouth, while the third is largely post-oral and forms the future optic 
lobes. The pre-oral and optic rudiments arise by delamination of the 
ectoderm, and are from the first covered by epithelium, while the adoral 
rudiments (which the author proposes to call the embryonic tentacular 
lobes) are for a long time naked. The ventral cords of the nervous system 
are also for a long time without any covering of epithelium. 
After the dotted substance has become differentiated in the ganglionic 
rudiments the supra-oesophageal ganglion contains three pairs of aggrega- 
tions of dotted substance corresponding to the three pairs of rudiments of 
which it is made up. It seems probable that the supra-oesophageal 
ganglion of all Insects is really made up of three ganglia, and thus, 
therefore, their head consists of at least six metameres. 
Thysanura of Bohemia. | — Herr J. Uzel gives an account of these in 
a monograph which deals with seventy-six species, and describes twelve 
new species — two of SmyntJiurus, one of Orchesella , two of Lepidocyrtus , 
two of Entomolrya , two of Isotoma , and three of Achorutes. 
y. Prototracheata. 
Peripatus Leuckarti.J — In his additional notes on this interesting 
form, Mr. J. J. Fletcher calls attention to its existence in the midst of 
“ the bleakness and winter snow of Mount Kosciusko,” N.S.W. The 
prevalent colours of the species are indigo-blue and red, either of which 
may predominate ; the former passes into black in some specimens, and 
the latter into orange or yellow. There is a median longitudinal dark 
linear stripe running down the back, in the middle of which is a fine 
microscopic, sometimes interrupted, line free from dark pigment. It 
seems no longer doubtful that constant specific characters are not 
derivable from the pattern and coloration of P. Leuckarti. The author 
adds some useful anatomical details. 
S. Arachnida. 
Embryology and Phylogeny of Pycnogonids.§ — Mr. T. H. Morgan 
has made a study of the embryology of Tanystylum , Phoxichilidium, and 
Pallene empusa. The differences exhibited by the last may be considered 
as being due to an abbreviation of what is seen in the second of these 
genera. 
The author is of opinion that the Pycnogonids and Arachnids are 
* Zool. Anzeig., xiv. (1891) pp. 115-6. 
t SB. K. Bohm. Gesell. Wiss., ii. (1890) pp. 1-82 (2 pis.). 
X Proc. Linn. Soc. N.S.W., v. (1890) pp. 469-86. 
§ Studies from Biol. Lab. John Hopkins Univ., v. (1891) pp. 1-76 (8 pis.). 
