ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
537 
New Species of Malacobdella.* — Mr. U. Takakura describes M. 
japonica sp. n., which lives in the mantle cavity of Mactra sachalinensis. 
It is interesting to notice that out of 56 shells examined, 54 were found 
to be infected. As Kennel found in Cyprina islandica, the adults always 
occur singly. The Japanese species differs from M. grossa mainly in its 
short rhynchocoelom, in possessing an acetabular instead of an anal com- 
missure, and in some peculiarities of the vascular system. 
New Land Pianarians.f — Mr. T. Steel describes seven new species 
of Geoplana from Australia, and G. trifasciata sp. n. and Bhynchodemus 
scriptus sp. n. from Fiji. The author has some interesting notes on 
preserving. The worms are best killed with very weak spirit. After a 
short dehydration with strong spirit, they may be put into chloroform or 
kerosene or carbolised oil, if a retention of the colours is particularly 
desired. 
Incertae Sedis. 
Structure of Actinotrocha.J — Mr. A. T. Masterman gives a short 
account of the history of research and opinion in regard to this fascinat- 
ing larva, and states in detail the results of his own investigation. 
Passing over his description of external form and the like, we may notice 
first his very full account of the nervous system. It consists of the 
following parts : — 
(1) A central ganglion lying in the front collar region and between 
this and the pre-oral lobe, with the epiblast immediately in front de- 
pressed to form a neuropore. 
(2) A ring round the posterior part of the collar, continued from the 
ganglion dorsally and ventrally, giving off fine double groups of nerve- 
tracts to the anal end of the body. 
(3) Groups of fine nerve-tracts continued dorsally along the trunk 
from the hind end of the collar to the anal end of the body. 
(4) A ring round the anal end of the trunk, into which the dorsal 
and ventral tracts lead. 
(5) A ring round the edge of the pre-oral lobe, joined at each side 
to the ganglion, and in the median front region, by three main tracts 
running in the mid-dorsal line forwards from the ganglion. 
(6) A diffuse plexus of fibres at the base of nearly all the epiblastic 
layer, conspicuous among which are the fibres of the ventral collar area, 
which pass forwards and dorsally to meet the ganglion. 
Mr. Masterman gives a circumstantial account of the development of 
the “ sub-neural gland.” During development the epiblast becomes 
tucked in at the mouth ; and on the mid-ventral line of the hood, ante- 
rior to the mouth, there is formed a small depression, which deepens, 
increases in size, and is carried further inside the buccal cavity. 
The development of the two “ notochords ” is described at length. 
The organs themselves arise from a pair of evaginations of the antero- 
lateral walls of the pharynx, which gradually become longer and deeper 
till they extend forward in close contiguity with the mesentery between 
the collar and the pre-oral lobe. They have no connection whatever 
* Annot. Zool. Japon., i. (1897) pp. 105-12 (1 pi.), 
t Proc. Linn. Soc. N.S.W., xxii. (1897) pp. 104-22 (2 pis.), 
j Quart. Journ. Micr. Sci., xl. (1897) pp. 281-339 (5 pis. and 14 figs.). 
2 p 2 
