386 Dr. Strahl on new Thalassine from the Philippines. 
aborted that the scale becomes small and inconspicuous (Gauco- 
thoé, Axius) (?), but it may also entirely lose the scale, when 
the armiger alone makes its appearance. In Lithodes aretica, 
also, which, however, does not belong to this group, it may be 
mentioned in passing, only the armiger exists. 
To complete the account of the relations of the individual 
antennal joints, I will add here that the articulating axis of the 
third joint is again directed from aboye downwards, and there- 
fore cuts that of the second antennal joint at a right angle. 
This relation of the articulating axes also occurs elsewhere; for 
example, in the chele of Lupa, Platycarcinus, &c., the arti- 
culating axes between the brachium, carpus, and manus each 
form a right angle with that of the next joint. But a peculiarity 
of the articulations of the antenne is, that on the bent side, in 
the soft chitinous tissue of the joint close to the sinew of the 
flexor muscles, there is a sac, into which it is probable that a 
portion of the articular skin folds itself during flexure. This 
character is important in determining whether a joint belongs 
to the antenna or the flagellum. My investigations in this 
direction show that both the outer and inner antennz always 
consist of three joints, as has already been asserted by Kroyer 
as a result of the embryology. Accordingly the outer antennz 
of the Scyllaride is by no means four-jointed, as is generally 
supposed; it is only three-jointed, as in the allied Palinuride, 
The joint supposed to be the fourth joint does not exhibit the 
peculiar articulation of an antennal joint, and is therefore a 
flagellar joint. The Palinuride, consequently, have a many- 
jointed flagellum on the outer antenna; the Scyllaride a one- 
jointed flagellum only. 
The joints of the antennze of Callianassa mucronata are not all 
of equal length; the first joint is the shortest; the second and 
third are each nearly twice as long. 
The external maxillipeds are opercular, without palpi. The 
first pair of feet is torn away; the second is didactyle. The last 
joints of the posterior ambulatory feet are beset with strong 
stiff hairs more abundantly than in C. uncinata. The abdomen 
exhibits no peculiarities; the central tail-fin is rectangular, 
broader than long; the lateral appendages, on the contrary, are 
longer, and form a wide-spread fan. The abdominal feet resem- 
ble those of C. uncinata. 
In company with the specimens just described there is a 
smaller one, about 5 lines in length, the characteristic frontal 
point of which shows that it belongs to the same species. It 
possesses the first pair of feet ; and from this we may fill up the 
gap. This pair of feet bears chele, and is the strongest of all; 
the left foot is stronger than the right one. The hand is hairy, 
