ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
185 
segments is not equal on the two sides of the body of one and the same 
individual. This waut of symmetry is very common in Bispira voluta- 
cornis ; common in Sabella pavonina , and less common in Branchiomma 
vesiculosum and Basychone bombyx. At present the author is content to 
signalize the facts without waiting for the law which governs them ; but 
they are so numerous, and proportionately so common that it is impos- 
sible to consider them as anomalies. It is very probable that examples 
of asymmetrical growth will be found, on search, in many other 
families of the Polychseta. 
Alciopidae of Messina.* — Prof. E. Hering gives an account, with 
many anatomical details, of seven species of Alciopa. He recognizes 
two well-marked groups ; in one the worms are colourless and transparent, 
while the tentacles and cirri are less developed than in other groups, 
where the body is less transparent and sometimes of a yellowish colour. 
Some additions are made to the earlier synonymy. 
Nephridiopores of Earthworms-! — Prof. A. A. W. Hubrecht having 
observed considerable differences in the position of the nephridiopore of 
Lumbricus and AllolobopTiora, and learnt that Claparede and Borelli had 
already called attention to the variations, gives some account of his Own 
observations. He is able to confirm the statement of Borelli that in one 
and the same individual the nephridiopores may lie just above the 
second seta, just above the fourth seta, or in the space between the fourth 
seta and the dorsal pore. 
With regard to the significance of these facts as bearing on the 
archaic condition of the nephridia in earthworms, Prof. Hubrecht points 
out that Beddard and Spencer have accepted the view, to which Benham 
inclines, that the “ plectonephric ” arrangement of the nephridia is the 
more archaic, while Bay Lankester and Horst think that the “ mega- 
nephric ” arrangement is the older of the two. 
The author urges that the inconstancy in the position of the nephri- 
diopores is an argument in favour of the hypothesis that two (or perhaps 
even three) pairs of large nephridia were originally contained in each 
segment, and that of these two pairs one had its nephridiopore above the 
outer, the other above the inner couple of setae. He urges more compe- 
tent specialists to test his views in different genera, and points out the 
support which the facts adduced give to the suggestion made by 
Lankester in 1865 that nephridia might be adapted to the service of the 
generative system. 
Nephridia of Megascolides4 — Prof. F. Vejdovsky has studied the 
development of the nephridial system in Megascolides australis. The 
youngest embryo, sent to him by Prof. Baldwin Spencer, was 36 mm. in 
length, obviously too old to show the beginnings of the nephridial 
apparatus. In the hindmost segments the praeseptal funnel rudiment 
was seen passing into the postseptal strand which ran along the dissepi- 
ment to the dorsal line, and ended with a simple coil. The funnel- 
rudiment did not show any canal or cilia, the postseptal strand and the 
dorsal coil were also solid. In the segment in front, the dorsal coil 
* SB. K. Akad. Wiss. Wien, ci. (1892) pp. 713-68 (6 pis.). 
t Tijdschr. Nederl. Dierk. Vereen., iii. (1892) pp. 226-31 (1 pi.). 
X Arch. f. Mikr. Anat., xl. (1892) pp. 552-62 (1 pi.). 
1893. 
o 
