ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
459 
the name Megascolex be applied to such forms as have the line of setae 
interrupted, and the clitellum occupying more than three segments, 
while Perichseta will apply to those in which the line of setae is con- 
tinuous, and the clitellum consists of three segments only. The fol- 
lowing new genera are proposed for species already described : Diporochseta, 
Anisochseta , and Hoplocheeta. With regard to the distribution of the 
setae in Chaetopods the evidence afforded by the Oligochaeta favours the 
view that a continuous circle of setae is the archaic condition. Notes 
are added on the nephridia, the spermathecae, and the glycogenic organs, 
additions are made to our knowledge of Perichseta biserialis , while 
P. forbesi , from New Guinea, and P. vaillanti, from Manila, are described 
as new. 
Segmental Organs of Hirudinese.* — M. H. Bolsius gives an account 
of the segmental organs of the Leeches. In all, the cavities of these 
organs, with the exception of the vesicle at the lower end, are intra- 
cellular cavities. In Hirudo and Aulastomum the organs consist of a 
glandular and of a collecting part ; the former contains a network of 
anastomosing canals, and these canals receive the chief trunks of a 
system of intracellular vessels, which groove the cytoplasm of most of 
the cells. The network itself communicates with the collecting canal 
by an apparently small number of branches. This collecting canal, 
which is formed of perforated cells placed end to end, does not extend 
as far as the superior part of the gland which abuts on the testicle. It 
opens below into a urinary bladder which is lined by epithelium. This 
vesicle has a sphincter ; its orifice pierces a cell — “ the cellule-porte ” — 
which forms the boundary between the intercellular and epithelial 
system of the bladder, and the intracellular system of the segmental 
organ. 
In Nephelis and Clepsine the segmental organ has the form of a 
ribbon made up of a single chain of cells. This chain is perforated by 
three canals of unequal length ; they arise in the cytoplasm of certain 
cells by a system of branching analogous to that of Hirudo and Aula- 
stomum. The three canals appear to unite, and the single canal opens, as 
in Hirudo , by an orifice in a single cell. The urinary bladder is greatly 
reduced, especially in Clepsine ; this bladder has no sphincter. 
In the structure of the cells, attention may be drawn to the nuclei, 
which contain an abundance of caryoplasm, much reticulated ; they 
contain a nuclear nucleolus which often possesses a distinct membrane, 
when it may be known as a “ nucleole-noyau.” In Clepsine the nuclei 
are often morula-like, and bear prolongations which are often cylindrical. 
The membranes of the cells and nuclei are dotted, as is also the wall of 
the internal canaliculi ; the trabeculae of the cytoplasm are inserted into 
these membranes in such a way as to establish an intimate relation 
between the canals and the reticulum. The trabeculae of the cyto- 
plasmic reticulum do not start from the nucleus as their principal 
centre, but from all the canals and internal canaliculi. In some of the 
canals there is a striated plate on the inner surface. 
The cells are very intimately connected with one another. In the 
glands of Hirudo and Aulastomum they communicate by the system of 
* La Cellule, v. (1890) pp. 369-436 (3 pis.). 
2 k 2 
