The dots in the ear are usually quite weak, but may sometimes appear nearly as strong as those in the Type IV. This is a typical Type III example.
The dots in the ear are usually quite strong and distinct. This is a typical Type IV example.
The total number of dots in the ear of the Type III and Type IV stamps appears consistent, at least in the opinion of this author. Since the dots have been reinforced in the Type IV stamp, there may be an appearance of more dots, but in reality a strong printing on a Type III will show an equal number of dots as the Type IV example here, though perhaps somewhat weaker. It may be difficult to tell a weakly printed Type IV from a strongly printed Type III based on the dots in the ear alone.
We have noticed another artifact of the Type IV stamp, namely that the ear itself seems to have been widened slightly, clearly evident in the scans above. This may account for the extra dots in ear description.
All the Type III examples are from the same scanned stamp from plate number 146, and all the Type IV examples are from the same scanned stamp from plate number 762.