I have found sources claiming as such, but none authoritative.

Although the structure resembles a placental mammal's scrotum, one cannot assume.

However, I am curious to find out what exactly it is since it seems oddly placed anatomically.

The following is a link to a baby echidna (puggle) at the Taronga Zoo; hopefully you will see what I am referring to.

http://youtu.be/SGleaTJoy1U?t=34s

The bumps are its lower jaw as stated in this article.

Synapse Science Magazine: Weird and Wonderful: Tachyglossus - The Real Easter Bunny (http://synapsebristol.blogspot.com/2013/02/weird-and-wonderful-tachyglossus-real.html)