ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
193 
blood in earthworms. He does not give any account of its general 
appearance but gives a figure which appears to be excellent. After 
some considerable additions to the details of our knowledge of various 
organs, the author proceeds to propound his new theory of the circulation. 
According to this, so long as the modified anterior extremity (of 
about the first twenty segments) remains intact, it is possible to remove 
any of the posterior segments without interfering at all with the circu- 
lation, in other words, there are signs of a metamerically segmented cha- 
racter of the vascular system, in all but the “cephalized” anterior region. 
The blood appears to enter the dorsal vessel in each posterior segment 
through dorso-intestinal, and to leave it by dorso-tegumentary vessels ; the 
latter are always small as compared with the former (of which, indeed, 
there are in many worms two pairs in a number of segments), and it is 
probable, therefore, that more blood enters the dorsal vessel than leaves 
it in each posterior segment. This excess is passed forward to be sent 
out in the cephalized region. With regard to the supply in the ventral 
vessel, all the blood which enters it comes from the hearts, and all the 
ventro-tegumentary branches appear to be efferent vessels. Contrary 
to the ordinarily received opinion that all the blood in the ventral 
vessel flows backwards, Prof. Bourne is of opinion that in front of the 
heart the direction of flow is forwards. 
As to the capillary networks, it seems that the afferent vessels of the 
peripheral networks are in all cases branches of the dorsal and ventral 
vessels, while their efferent vessels are branches of intestino-tegu- 
mentary vessels, and the afferent branches of the intestinal networks are 
branches of the intestino-tegumentary trunks ; the efferent vessels of this 
last system are branches of either the typhlosolar, the supra-intestinal, 
or the dorsal vessel, so that blood coming from them is driven either 
into the hearts or into the dorsal vessel at its anterior extremity, in either 
case into peripheral networks ; from these the blood passes into the 
intestino-tegumentary system, and once more into the intestinal capil- 
laries. Prof. Bourne points out that a merit of this theory is that it 
exhibits the vascular system as a perfectly metamerically segmented 
organ, the portion of it which is contained in the cephalized region 
representing, as a whole, almost exactly the portion contained in any 
other segment of the body ; it has undergone a synthesis, and certain 
additional structures, the hearts, have become developed in its region. 
New Genus of Earthworms.* — Dr. E. Horst has a preliminary note 
on a new earthworm brought by Prof. Max Weber from the Malay 
Archipelago. The genus is to be called Glyphidrilus (6r. Weberi) on 
account of the clitellum being provided on each side with a folded, 
crenulated ridge. One to three pairs of spermathecae are to be found in 
each segment from xiv. to xix., and all were densely filled with 
spermatozoa. The new genus is specially characterized by the back- 
ward position of the male genital pores, the situation of the spermathecae 
behind the other genital organs, and by the presence of more than one 
pair of them in each segment. The male pores are between segments 
xxvi. and xxvii., and their position in the intersegmental groove is 
also of rare occurrence. 
1891. 
* Zool. Anzeig., xiv. (1890) pp. 11-12. 
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