"Porcupine" Catepillar...What Species?

[cherokee at hctc.net]

Hi!
	We live in the Texas Hill Country in Kendall County.  My
daughter found a large black "porcupine" like catepillar,
approximately 2 inches in length and when it curls up you can see
orangish-red bands on it.
	I looked quite a bit on the net but was unable to come up with
a picture of this species.  I thought, in my amateurish search, that
it may be of the Sphingidae moth species, but, really this is not my
area of expertise at all.
	I would really like to identify this for my kids and if anyone
on here could help me out, I certainly would appreciate it.  Also, if
anyone knows of a site on the internet which would show a picture,
too.
Thank you so very much in advance for your help!

Sharon ;^)
cherokee at hctc.net