Class 3ab1 was issued by all the Henry III long cross mints except Durham; examples from London and Canterbury are shown below.  For coins from the provincial mints please use the following links:  

Bury, Bristol, Carlisle, Exeter, Gloucester, Hereford, Ilchester, 

Lincoln, Newcastle, Northampton, Norwich, Oxford,

Shrewsbury,  Wallingford, Wilton, Winchester  York.

This class includes coins with no punctuation mark on the obverse after REX, and coins with a pellet or a colon.

The illustration above shows a typical example of 3ab1 : showing mintmark type 3 - and a straight-limbed X.  The characteristic feature for type 3ab1 being a bust transitional in style between 3a1 and 3b. Bust is less pointed than 3a, but not as rounded as in class 3b.