740 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
animal within it, proceeds to coil up like a spiral spring. This is, of 
course, an effectual protection against the intrusion of enemies. The 
worm, which belongs to an undetermined species, was obtained from 
Jersey. 
Distribution of Magelona.* — Mr. E. A. Andrews adds the coast of 
North America for M. papillicornis found off the British coast ; the 
worm has also been taken at Wimereux and off the coast of Brazil. Its 
wide distribution would be remarkable, as the adult lives buried in the 
sand, were it not for the long duration of the pelagic larval stage which 
allows of transport by ocean currents. 
Clepsine plana.f — Prof. C. 0. Whitman gives a detailed description 
of this new American species. In the course of his remarks he draws 
attention to the hitherto overlooked fact that, among Leeches, metamerism 
has undergone modification in two opposite directions. Variation by 
centripetal reduction of the number of rings is universal ; variation by 
multiplication of rings characterizes, as a rule, only the higher forms, 
such as Hirudo and Nephelis. Clepsine rarely exhibits the second mode 
of variation, but a physiological explanation can be offered of the 
difference in this respect between the Clepsinidae and the Hirudinidse. 
Hirudo swims, and for this purpose a long flexible body is required ; 
Clepsine habitually creeps, and for this mode of locomotion supplemen- 
tary rings have not been essential. A preliminary and not a comparative 
description of the new leech is, for the present, offered. 
Further Researches on Segmental Organs of Hirudinea.J — Prof. H. 
Bolsius gives an account of his further researches on the segmental 
organs of various Leeches. In all the forms examined the terminal 
funnel of the organ is absent, as Vejdovsky has stated for the adults of 
all the species which he studied. Hsemopis vorax differs from Hirudo 
medicinalis and Aulostomum gulo in having the organ less closely packed 
and more coiled ; a single layer of glandular cells surrounds the cells 
which contain the collecting tube. In Clepsine and Hemiclepsis the three 
canals take their origin from ramifications or lacunae : both these 
form three independent systems, one for each canal ; they may pass from 
one cell to another by a special prolongation, which is distinct from that 
which conveys an earlier formed canal. The three canals finally unite 
into one collecting canal, and the union is effected at a varying distance 
from the inferior orifice in various species. 
The protoplasm in the cells of Clepsine and Hemiclepsis is sometimes 
divided into areas which separately surround each canal. In most cases 
these areas are not limited all round, but fuse partly with the ordinary 
protoplasm of the body of the cell. The boundaries of the areas never 
have a well-marked membrane. The typical mode of union of the cells 
is by as many separate prolongations as there are canals in the cells. 
* John Hopkins Univ. Circ., x. (1891) p. 96. 
t Journal of Morphology, iv. (1891) pp. 407-18 (1 pi.). 
X La Cellule, vii. (1891) pp. 1-77 (3 pis.). 
