164 
ZOOLOGY OF THE FAR EAST. 
third and fourth annuH, the next deepest the one separating the second and third 
annuh. Then comes the furrow between the fourth and fifth annuli, while that be- 
tween the first and second is invariably the shallowest of all. When we trace the 
somites from the middle region towards both extremities it is always the shallowest 
furrow, i.e. the one separating the first and second annuli, that disappears first, 
while the deepest one, that between the third and fourth, continues to exist so long 
as the somite is at all subdivided into annuli. From this we might safely infer that 
when a somite is biannulate the rings represent i + 2 -|- 3 and 4 + 5 of the typical 
quinqueannulate somite respectively (a). Similarly, in a triannulate somite the rings 
are i-t-2, 3 and 4+5 {b); in a quadriannulate somite they are 1+2, 3, 4 and 5 (c). 
1 + 2 
1 +2 
§3 
&: 3 
4+5 
4- 
"5" 
4 
5 
a. ^ c cL 
Diagrams showing stages in the formation of quinqueannulate somite in Hirudinea. 
(Dotted area indicates the position of nerve-ganglion). 
This agrees remarkably well with the result obtained from a comparative study of 
Japanese leeches, which I read at a meeting of the Tokyo Zoological Society several 
years ago. As I hope to deal with the subject more fully elsewhere, I confine myself 
here to state that our new genus with its unique character throws considerable light 
not only on the external morphology of the Gnathobdellids but of the Hirudinea in 
general. 
Internal Anatomy. The alimentary tract resembles, on the whole, that of 
Haemopis, the only considerable difference being in the size of the jaws. These 
are very small, only about 0 2 mm. in diameter, and are provided each with two 
rows of three or four minute denticles along the middle part of the margin. In 
sections a bundle of ducts of unicellular glands is seen opening on the edge of each 
jaw. 
The stomach, including the lateral sacculations, was found completely filled with 
a very hard homogeneous mass of a brownish colour, which became opaque white when 
placed in water. No solid particles, such as residue of aquatic worms, setae, cuticle, 
etc., were detected in it. I am inclined, therefore, to believe that our leech lives by 
sucking blood of invertebrate animals. 
So far as I could count, there are eight pairs of testes, each placed behind and 
somewhat beneath the lateral sacculation of the stomach. The vas deferens forms a 
considerable mass of convolutions on each side of the male pore. The female organ 
seems to correspond in structure to that of Haemopis. 
Locality. Small streamlet on the Peak, Hong Kong, ca. 1000 ft. Dec. 15, 1915. 
