ARACHNIDS., 565 
found a small papilla, which may be considered as the rudiment of 
a penis. Also in some Acarina a short penis is present. In Pha- 
langium, on the other hand, there is a long horny penis which can 
be extended from the body at the same part as the ovipositor in 
the female, and through which the ductus ejaculatorius extends ; 
at the upper extremity of the glans is a small hooklet. In the 
spiders the two efferent vessels, arising from the blind tubes that 
secrete the seed, run towards the base of the abdomen, where they 
open, without any copulative organ, between the gills. The organ 
of copulation lies very distant from this opening. In the spiders, 
namely, the last joint of the feeler is excavated like a spoon, with 
various appendages in addition, different in different species, and a 
horny, curved filament connected, which lies concealed in the exca- 
vation, and can be extruded from it. With this club of the palpi, 
the male, at the time of pairing, touches the sexual parts of the 
female, having previously moistened it with a drop of seminal fluid 
from the opening of the vasa deferentia. This is thus the copula- 
tion itself, and by no means, as TREVIRANUS supposed, a prelimi- 
nary sport to excite the sexual passion: this is the copulation itself, 
which Lister, De Grrr, Lyonet, and others, described so fully 
and so interestingly!. The danger of being cruelly put to death by 
the female spider causes the male to make his approaches to her 
with anxious caution, and after the congress to betake himself 
rapidly to flight. 
In the development of the arachnids from the egg, after the 
germinal vesicle has disappeared, there appear to occur, as In many 
other animals, clefts and grooves in the yolk-mass. The ger- 
minal membrane or disc grows slowly round the yolk, closing 
finally on the dorsal surface. Before this closure is completed, 
the commencement of the embryo appears on the ventral surface of 
the yolk. Here are seen, at least in the embryo of the scorpions 
according to the observations of RaruKs, different thickenings 
lying in pairs near each other in a row, which are the beginnings 
of the segments of the body. From the mucous layer of the ger- 
minal membrane arises the intestinal canal, which at first is not 
' See, for instance, Lyoner in his translation of LESSER Théol. der Ins. 1. p. 184, 
and in his Recherches, pp. 73—75, and WaALCKENAER Hist. nat. des Aranéides, v. 8, 
respecting Theridion benignum. See also Owen Lectures on comp. Anat. of invert. 
Anim. p. 264, 2nd ed. p. 462. 
