Something is poisonous if it makes you sick when you eat it. Something is venomous if it makes you sick when it stings you or injects venom through a fang.
Almost all Spiders have one kind of venom or another. Almost no spiders have enough venom to kill a healthy adult human, however, there are lots of spiders that have enough venom to make you hurt for a while. There are only two main kinds of spiders that you really have to worry about (particularly if you have kids) in the U.S. They are:
•Black widow spiders
•Brown recluse spiders
Neither one of these spiders fits the description you give.
Araneus diadematus(AKA cross spider) is the only spider i can think of that i know of that is brown/black and has a cross on its back. Here are some photos. http://www.nicksspiders.com/nicksspiders/araneusdiadematus.htm
A garden cross spider, Araneus diadematus. Source: Google search for spider cross back
Have seen a very small spider with 4 white dots and 1 red dot. Not a red back. Ta ~Snaff
The answer is a brown camel spider.
A brown spider that has a white diamond on its back is known as a Parson spider. This spider does have a mildly venomous bite.
The brown recluse spider is the kind of spider that has a brown oval mark on its back. This spider's bite is extremely deadly to animals and humans.
Yes, These Spiders Are Very Poisoness. But These Arent The Ones You Should Worry About. It's The Red Back Spider. Usually Mistaken For The Black Window.
a spider known as a cross spider usaually found in the uk
The spider that is black with a white crescent on its back is the Brown House Spider. This spider is often confused with the red-back spider.
An Arrowhead spider is brown with a green back. This spider is also known as a Triangle Orb Weaver. This spider is not venomous.
your mummy spider
A Garden Spider