200 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
wall forms folds and evaginations. They have never yet been properly 
described, and the details are too numerous for mention in the author’s 
present, preliminary notice. 
The Palps of Rhynchota.* — Herr E. Schmidt finds palps on the 
underlip of Nepa and Eanatra, yet the absence of these palps is usually 
stated as characteristic of Rhynchota. He finds that various entomo- 
logists, from Savigny onwards, have noticed these structures, but 
their homology has not been recognized. The author also discusses 
the systematic relations of Nepidse and Belostomidre, and concludes 
that they are more nearly related to one another than to any other group. 
Embryonic Development of Phyllodromia germanica.t — Herr N. 
Cholodkowsky has been for four years engaged in the study of tho 
development of Phyllodromia ( Blatta ) germanica, and here exposes some 
of his results. With regaid to those of most general interest we may 
note that lie finds that the head of Insects contains more than four proto- 
zonites, and probably six, one of which is pre-oral and the others 
post-oral. The antennae belong to the first post-oral segment and are 
completely homologous with the other ventral extremities ; they do not 
correspond to the antennae of Peripatus, but rather to the cbelicerae of 
Spiders, and perhaps to the second pair of antennae in Crustacea. As 
the possibility that a number of segments in the germ-stripe of various 
Arthropods have disappeared cannot be denied, it is at present impos- 
sible to speak definitely as to the homology of the mouth-parts of the 
various classes of Arthropods. The abdominal appendages of the 
insect germ-stripe (cerci included) are homologous with the thoracic legs. 
It is not important whether they are attached to the middle, side, 
anterior or posterior margin, so long as their cavity is directly con- 
tinuous with the cavity of the somite to which they belong The fact 
that the abdominal appendages are generally unjoin ted is not an argu- 
ment against their being appendages, for, e. g. the mandibles are alw'ays 
unjointed. Many of the abdominal appendages of larval and imaginal 
insects are homologous with thoracic legs, although they are ontogeneti- 
cally secondary. 
The primitive function of the first pair of abdominal appendages 
was, like that of the rest, ambulatory, and we may be sure that tho 
ancestors of Insects were homopodous and not heteropodous. The poly- 
podous Insect-larvae are no more to be derived from the hexapodous 
than they from the polypodous ; the two forms were developed indepen- 
dently of one another. The embryonic investments of Insects probably 
correspond to the remains of the trochophore. The author is inclined 
to believe in the, at least, diphvletic origin of the Arthropoda ; the 
Crustacea are characterized by their naupliiform larva, while there is a 
striking likeness between the embryonic development of Insects and 
Peripatus ; the ancestry of the former would be found among the 
Marine Annelids with a trochophore stage, and of the latter among 
terricolous or freshwater and more oligochaete-like worms. He ex- 
presses great doubts as to the relationship of the Marine Poecilopoda 
with the terrestrial Arachnoidea. 
* SB. Gcsell. Nat. Freunde Berlin (1891) pp. 46-54. 
t Mem. Ac Imp. Sci. St. Petersburg, xxxviii. No. 5 (1891) 121 pp. (G pis.). 
