Related Clues:

• Refusing to change one's mind
• One might, to be sure, claim that this was the insect of 3 down
• Can one be so sure that this was the father of all insects?
• Can one be so positive that that's an insect mother?
• One may be positive that that was the very first insect
• One may be positive that this was the first of all the insects
• How a 18 down may may positively get to be six feet long
• One may be definite that this was the first of all the insects
• First man gets firm over the insect
• Seems there's a scrappy mother in the Pict, but not according to theory
• Can you be positive that the fatherly fellow is in at this?
• Positively the first insect of them all?
• One may be positive that this was the father of all insects
• Positively the first insect of all
• One may be positive that he was the first of the first of 10 across