624 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
of tlie purely morphographic method when unchecked by a consideration 
of the facts of functional adaptation. 
Describing next the structural peculiarities of this form, he draws 
attention to the great elongation of the second pair of antennae which, by 
their apposition, give rise to an organ which the author calls the antennal 
tube. The first writers who appear to have given a real explanation of the 
use of the antennae were David Eobertson and P. IT. Gosse, who independ- 
ently gave explanations which are not far from the truth. Mr. Garstang 
has himself made a number of personal observations and experiments. 
The crabs in question have a marked habit of burrowing, and during the 
daytime they remain concealed from all observation. At night, however, 
they move about actively as though in search of food. If a little Chinese 
ink or finely powdered carmine be added to the water in the neighbour- 
hood of the antennal tube of a masked crab, it will be invariably found 
that the current which goes through the antennal tube is from above 
downwards and not vice versa. The direction of this current through the 
branchial chamber is the reverse of that which has hitherto been recog- 
nised in all other decapod Crustacea, where it is from behind upwards. 
The current of the buried Corystes may therefore be spoken of as a reversed 
current. The author describes and explains the causes for the currents 
of respiration, and points out that the burrowing habit is useful as a 
method of concealment from enemies. The elongation and smoothness 
of the carapace and the elongated claws of the hinder legs are all features 
usefully correlated with the specialisation of the crab for a sand- 
burrowing existence. The elongation of the antennoe and the arrange- 
ment of the hairs upon them, the double bend of their basal joints, the 
structure of the parts bounding the mouth-chamber, and the arrange- 
ment of hairs upon them are characters which, in conjunction with the 
reversal of the respiratory current, adapt the respiratory mechanism of 
the crab to a sand-dwelling mode of life. The antennal tube enables 
the crab to draw its supplies of water from that above, while the 
arrangement of hairs is such as to constitute a sieve, which keeps the 
sand away from the respiratory organs. The upright position of the crab 
is a most unusual feature, but may be easily correlated with the forma- 
tion of an elongated antennal tube. 
Cleavage of Egg of Virbius zostericola.* — Mr. F. P. Gorham has 
a short notice on the history of the egg of the green shrimp, which,, 
unlike most of its allies, is remarkably favourable for the study of early 
cell-lineage. Females bearing eggs in all stages of development can be 
obtained throughout the summer months, and eggs removed from the 
females will continue their development in watch-glasses under the 
Microscope, if the water is occasionally renewed. The early segmenta- 
tion of the egg is total and regular, and at first it is impossible to 
distinguish between the animal and vegetable poles. 
In the great majority of cases, the first cleavage plane cuts the egg 
at its equator. The second cleavage takes place in one of two ways ; 
the spindles either lying parallel or perpendicular to each other. This, 
of course, gives rise to two radically different methods of arrangement 
of the later blastomeres. Three types of different segmentation are 
distinguished, and the invaginating cells are found to arise from different 
* Journ. Morphol., xi. (1895) pp. 741-5 (1 pi.). 
