Hatched after nearly 40 Days of Incubation?!

[NatJ]

Thank you so much. Yes, i googled Delaware ,she looks exactly like that. So,i assume there is only 25 percent chance of having a delaware styled chicken if two black sexlinks are bred?

I think it's closer to a 1 in 16 chance of looking like a Delaware.
The other possibilities would be:
1 in 16 chance of silver columbian (like Delaware but without the white barring)
1 in 16 chance of red columbian (like a Rhode Island Red or New Hampshire)
1 in 16 chance of barred red columbian (like a Rhode Island Red but with white barring)
3/8 chance of solid black (no white barring, but may have gold or silver leakage)
3/8 chance of black with white barring (may have gold or silver leakage too)

If I did my arithmetic right, that should add up to 16/16 or 100%

Breaking it down into individual genes:
50% barred, 50% not-barred
75% black, 25% columbian pattern
50% silver, 50% gold

The Delaware appearance is in the 25% Columbian pattern, 50% of those being silver, 50% of those being barred. So .25 * .5 * .5 = .0625% chance, which is the same as one in 16.

 

[Nayday]

I had a black sex link hen, she died of heart attack due to a fox attack. I cried a lot Anyhow i decided to incubate her egg to have her memory. So i took her eggs out of the fridge which was kept for few days and kept in hay ,turning every day for 2 weeks .When i got my incubation machine, put it inside and the egg hatched on 21 day. I knew in less than a week, from that chick behaviour that she is a hen. As i know my chickens behaviour and traits very well. She is now 4 months ,not yet laying.

Puzzling question : Is she a new breed. Because her parents were both black sex link. And she was born yellow and now off white colour with a beautiful dotted neck like bald eagle.