Looks more like Cryptophis nigrescens to me, although it's hard to be sure based solely on these photos of ant-covered specimens. Did you happen to take any shots of the underside or close-ups of the head? Please add them if you did.
Yes, that definitely helps. Thanks Lisa. I'm sure it's a Small-eyed Snake after seeing the additional photo of the belly. A key difference between these two similar looking species is the belly of the Red-bellied Black Snake is strikingly barred with regular black bands, as there is a black posterior edge to each belly scale. The Small-eyed Snake doesn't have these distinct black ventral bands.