
Macracantha arcuata, head 2, Heesch, Netherlands
Old low quality specimen, sorry.
This is a 7:1 macro (+crop) of the head of a female Macracantha arcuata, which are known for their lengthy spiny horns on the abdomen. Besides that, there's the pretty face as seen above.
The massive jaw-like structures are the chelicerae, consisting of a base and in the bottom the fangs. There are different types of chelicerae depending on species, apparently this one is called a "jackknife".

''Macracantha'' is a species of orb-weaver spider in the ''Macracantha'' genus. They can grow up to 10mm in length and have a hard, flat body with three spines coming from the abdomen.