98 DR. J. G. DE MAN ON THE PODOPHTHALMOUS 
frontal ridge, when examined under a lens. The convex ptery- 
gostomian regions are slightly granular, and the inflected sides 
of the cephalothorax are marked with some oblique elevated lines. 
The outer surface of the ischium-joint of the external maxillipeds 
presents an impressed longitudinal line, to which Mr. Hilgendorf 
first directed attention as a character serving to distinguish the 
species of this genus. In 7. Callianira this line is situated about 
the middle of the joint, and is directed a little obliquely, so that 
it almost coincides with a diagonal uniting the internal angle of 
the anterior margin of the joint with the external angle of the 
posterior margin. The outer surface of this joint is minutely 
punctate. In 2 hydrodromus this impressed line is situated 
much closer to the internal margin of the joint. 
The outer surface of the sternum and of the abdomen is faintly 
punctate. The male abdomen has a characteristic form. It 
gradually and rather rapidly narrows towards the posterior margin 
of the penultimate joint ; the latter is nearly quadrate, and as long 
as broad at the posterior margin, its lateral margins being nearly 
straight. The terminal joint is distinctly longer than broad at 
its base; it is rounded at the tip, and the lateral margins are 
slightly concave immediately behind the middle of the joint, 
which therefore presents a characteristic form. In Z. hydro- 
dromus the penultimate joint is broader than long. 
T. Callianira belongs to the small species of the genus ; in the 
adult ova-bearing female specimen the distance between the 
epibranchial teeth measures only 15 millim. 
The anterior legs are very unequal, especially in the male; and 
the larger chelipede is found either on the right or on the left 
side. The outer surface and the upper margin of the arm are 
somewhat transversely rugose, and the anterior margin is some- 
what granular. The upper surface of the wrist is slightly rugose 
towards the external and internal margins; the latter is armed 
at the internal angle with an acute tooth. The larger hand is 
about as long (the fingers included) as the breadth of the cephalo- 
thorax, and twice as long as high (the fingers included). The 
palm itselfis but little longer than high at the base of the fingers ; 
its outer surface is convex, smooth, and slightly punctate, like the 
inner surface, and the upper and under margins are rounded. 
The lower finger is slightly deflexed, and the mobile finger is 
slightly arcuated, leaving a hiatus when closed ; both fingers are 
