Hi, this might be Dysdera crocata, a Woodlouse Hunting Spider.
That is an odd shape cephalothorax for D. crocata
I might suggest something like a small sheetweb spider, Linephidae.
You’re right, it is quite arched. The abdomen should probably be longer also.
This is a Broad-faced Sac Spider, Trachelas tranquillus.