ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
599 
his discovery, while studying the Agricultural ants of Texas, of the 
remarkable domed snares of what he has designated Epeira basilica. 
The second volume of this work is to deal with the courtship and 
mating of spiders, the early life and distribution of species, their senses 
and the relation of these to their habits, their enemies, and fossil 
spiders. 
Habits of Mygale.* — Herr C. Greve gives an account of the 
behaviour of a Mygale , which (along with four others, several millipedes, 
and a snake) was found at Moscow in the cavity of a log shipped from 
Honduras. After a voyage of some six months, the liberated spider 
showed a naturally large appetite, and devoured thirty cockroaches in ten 
days. Its hunger diminished, however, and for a while some enticement 
was requisite to arouse fresh appetite. Across the floor of the cage 
fine threads were spun on which the cockroaches were entangled. The 
spider’s activity was emphatically nocturnal, for during the day it 
usually remained lurking in a hole. Herr Greve observed it killing its 
prey, and noted that it sometimes left the corpses for future use. On 
the floor of the room it would run about like a mouse, and a morning 
douche-bath seemed to be enjoyed. Its power of vision was keen for 
objects above its eyes, but not for things on its own level. From his 
observations, Herr Greve concludes that the spider lurks in holes for 
prey entangled in the almost invisible snares spun round about. An 
unlucky fail injured his pet, and brought his interesting studies to 
an end. 
Water-Mite Parasitic on a Snail. t — Herr F. Koenike has a pre- 
liminary notice of Atax Ampullarise sp. n., a water-mite found living 
parasitically in the gills of a South American species of Ampullaria. 
Up till now species of this mite have been found parasitic only on 
Bivalve Molluscs. 
€. Crustacea. 
Variations of Decapod Crustacea.:]: — Mr. W. F. R. Weldon has 
investigated the average length of three or four organs which admit 
of accurate measurement, and the frequency with which the average 
length and every deviation from it occurred in one or two local races of 
Crangon vulgaris. The organs selected were four ; the total length of 
the carapace ; the distance from the posterior margin of the carapace to 
the front of the median spine; the length of the sixth abdominal 
tergum ; and the length of the telson. Four hundred individuals were 
obtained from Plymouth Sound, three hundred from Southport, and three 
hundred from Sheerness. It was found that not only does the average 
size of the carapace differ in different local varieties, but the range of 
deviation from that average differs also. Nevertheless the frequency 
with which the observed deviations from the average occur is in all the 
three observed cases expressed by a curve of error ; this was precisely the 
result predicted by Mr. Galton. 
Results similar to the above have been obtained from measurements 
* Zool. Jahrb., v. (1890) pp. 179-83. 
t Zool. Anzeig., xiii. (1890) pp. 364-5. 
X Proc. Roy. Soc., xlvii. (1890) pp. 445-53. 
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