Excerpt a Zoologica : — Entozoa. 47 



it is not Mougeotia glutinosa in an imperfect condition, is 

 proved first by the smaller diameter of its filaments, but more 

 especially by the position of the angles of flexion, these being 

 placed indifferently on either side of the filaments, and not on 

 one side, as would be the case were the filaments intended to 

 unite with each other, so that this arrangement of the angles 

 of the cells forms a positive obstacle to their union ; for even 

 were the cells all of the same length, which they are not, it 

 would still be impossible for the angles of one filament to 

 correspond so as to unite to form the sporangium with those 

 of another filament : and that the species is in itself perfect 

 and distinct in the condition indicated in the definition above, 

 is established by the invariable presence of spores in all the 

 filaments and the non-union of these. 



Found in great abundance in ponds in some of the brick 

 fields near Notting Hill. 



The genera Zygnema, Mougeotia, and Tyndaridea merge 

 through certain species into each other. Thus the genus 

 Zygnema passes into the genus Mougeotia through Zygnema 

 curvatum, this having relation with the one by its spiral tubes, 

 and with the other by its angular mode of conjugation ; and 

 the genus Mougeotia into the genus Tyndaridea through the 

 species regarded with doubt as the Conjugata gracilis of 

 Vaucher, in which the cells are at first filled with endochrome, 

 as in Mougeotia, which subsequently becomes divided into 

 two roundish masses, as in the species of the genus Tyndari- 

 dea. This transition of one genus into the other does not, I 

 think, affect the validity of either. 



Accurate figures of all the above species have been pre- 

 served, as well as of those already described in British works, 

 and all drawn to the same scale. 



X. — Excerpta Zoologica, or abridged Extracts from Foreign 

 Journals. By Dr. Felix von Bjsrensprung. 

 To Richard Taylor, Esq. 

 Dear Sir, 

 Anxious on quitting Germany to possess myself as soon as 

 possible of all information connected with physiology and na- 

 tural history, and aware from experience of the difficulty of 

 procuring many of the journals, and more especially the dis- 

 sertations published in that country, some of which are of 

 great value, I requested my friend Dr. F. von Baerensprung 

 to forward to me short notices of what appeared from time to 

 time. I have no doubt that these may be of as much interest 



