362 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
labyrinth may be considered as the representative of this tube, which 
has become very short and much widened. 
As may be gathered, the author considers that the structure of the 
excretory apparatus of the Crayfish is far from being typical, and is, 
indeed, exceptional amongst the Decapoda. It is very probable that the 
medium in which the creature lives is partly the cause of this difference ; 
Grobben has remarked that the antennary gland of the marine Cetochilus 
has a very short tube, while that of the freshwater Cyclops has a tube 
of extraordinary length ; so, too, among Annelids the marine Polychaeta 
have short segmental organs, while those of Oligochmta and Hirudinea 
are very long. This rule, however, is not absolute, for in Telphusa 
fluviatilis the excretory apparatus is not different from that of marine 
Crabs. There is a great variability in all, except the Brachyura, which 
form a very homogeneous group. In the Astacid® the septate, non- 
ramified saccule is free on its upper surface, while its lower is imbedded 
in the rest of the gland. The blood-supply comes from both the an- 
tennary and sternal arteries ; in the Lobster the labyrinth seems to 
exhibit a tendency to elongate into a spongy cord, and this becomes 
much more obvious in the Crayfish. In the Galatheid®, Thalassinid®, 
and Paguridae the saccule is ramified and enveloped by the labyrinth in 
which it is invaginated ; the saccular artery is the only important one, 
and serves to irrigate the gland. In the Palinurid® the upper surface 
of the saccule has a villous or mammillated appearance, and the saccule 
itself is much ramified ; the labyrinth opens widely into the bladder in 
such a way that, when its cavity is not traversed by trabeculae, it seems 
to be a scarcely differentiated diverticulum. Palinurus has an appended 
gland. In the Candidas the saccule is perfectly distinct from the 
labyrinth, or the latter is entirely absent. 
The quantity of fluid excreted is very considerable ; it contains 
homogeneous or refractive globules, vesicles, and a small amount of cel- 
lular debris. If the evacuation of fluid from a Maid be stopped the 
animal dies in from eight to fifteen days. The author distinguishes a 
carcinuric acid, which is allied to the carbopyridic acids, and this, joined 
to the presence of a leucomaine, as a normal and essential product of 
nitrogenous waste, is a remarkable and unexpected fact. 
Embryology of Homarus americanus.* — Mr. H. C. Bumpus gives 
an account of the earlier stages in the development of the American 
Lobster. The eggs are normally deposited during the months of July 
and August, and develope rapidly so long as the w r ater is relatively warm. 
The eggs are normally carried by the female from nine to ten months. 
The receptive apparatus of the female seems till now to have escaped 
detection. It lies at the posterior end of the sternum, and is a highly 
coloured heart-shaped body. The openings of the oviduct lie anteriorly, 
•while a keel-like piece stands as a w r edge between the wings, which are 
directed laterally and posteriorly. If these wings are forcibly depressed, 
a whitish substance is seen to ooze out between them and the keel ; this 
fluid, when examined, will be found to be spermatic. 
A full description is given of the ovary at various stages and of the 
ovarian egg ; the egg is primarily ectolecithal, but later on becomes 
*■ Journal of Morphology, v. (1801) pp. 215 62 ((> pis.). 
