I am weighing in on Cuckoo Marans 1.) Because that was what was ordered, 2.) the bars are not clean and even and 3.) she has the slate wash down the front of her legs. Now, this was most likely from a hatchery (I include MyPetChicken in the hatchery category), and therefore will likely not be under the perfect standard of the breed. It is probably not a Holland because they are not a very common breed and it is more likely to be a BR or a CM. Both the BR and CM lay brown eggs but the CM lays what is referred to as a chocolate brown egg. She is getting far enough along that you will know for sure soon enough. Please report back and let us know?