ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
633 
Leidy, but as no information was afforded regarding its internal struc- 
ture, European students have been in doubt as to where to place it. The 
author finds that Michaelsen was, even if by accident, right in placing 
Distichopus next to Fridericia. The form of the setae is easily derived 
from the straight internally-hooked type of Fridericia , while their 
arrangement in bundles is even more characteristic of the Eriderician 
plan. The post-clitellar region of the dorsal vessel, the colourless 
blood, the two kinds of peritoneal corpuscles, the large size and branched 
arrangement of the salivary glands, the simple alimentary canal, the 
character of the male ducts and of the nephridia, are all points which 
these two genera possess in common. The absence of dorsal setse from 
Disticliopus is not, in the author’s opinion, any reason for regarding it 
as allied to Anacliaeta. 
Yolk-Nucleus in Eggs of Lumbricus.* * * § — Mr. G. N. Calkins discusses 
the nature of the so-called Dotterlcern. He commences with acknow- 
ledging that a more explanatory name might be given to the yolk-nucleus, 
for it is not a nucleus, and the only excuse for the use of the term is the 
time that it has been before us. As is well known, two very divergent 
explanations have been given as to the origin of the yolk-nucleus, some • 
having said that that origin is cytoplasmic, and others that it is nuclear. 
Mr. Calkins comes to the conclusion that in Lumbricus it is not only of 
nuclear origin, but it is derived from the chromatin ; in fact, the yolk- 
nucleus may be said to be chromatin in the form of a mass of granules ; 
this granular mass disintegrates, and the parts form the yolk-plates of 
the egg after undergoing change in their chemical composition. 
Two new Lumbricidge from North America.! — Dr. H. Ude gives 
short descriptions of two new species of earthworms from North 
America, fuller descriptions of which will be published later on. Allo- 
lobophora Gieseleri was found at Savannah. The dorsal vessel has five 
pairs of lateral hearts, and the enteric canal has in the eleventh and 
twelfth segments an enlargement of its wall, in the folds of which there 
are calcareous crystals. Diplocardia verrucosa , from Nebraska, has an 
enteric canal with a double muscular stomach. 
Nemathelminth.es. 
New Variety of Heterodera Schachtii.! — Dr. W. Voigt describes a 
dwarf variety of this common parasite, found by Mr. Percival on the 
roots of hops in Kent. It appears to be an instance of particular adaj> 
tation to new conditions, and there are other similar cases. 
Eilaria labiata.§ — Dr. M. C. Francaviglia has made a detailed 
study of Filaria labiata Creplin, hitherto incompletely described. The 
male occurred on the pericardium, the female on the crop, of the black 
stork. 
Strongylus subtilis.jj — Dr. A. Looss gives an account of a hitherto 
unknown nematode parasite found in man in Egypt. It was discovered by 
* Trans. New York Acad. Sci., 1895, pp. 222-30 (5 figs.). 
t Zool. Anzeig., xviii. (1895) p. 339. 
t SB. Niederrhein. Ges. Bonn, 1891, pp. 94-7. 
§ Boll. Soc. Rom. Zool., iv. (1895) pp. 93-108. 
|| Centralbl. f. Bakteriol. u. Parasitenk., l te Abt., xviii. (1895) pp. 161-9 (1 pi.). 
