Some herpetologists have considered whether they should be classified as a new species based on locality. The name recently suggested for this morphological variant, is "Corallus batesii" . Specimens from the Amazon River basin tend to grow the largest, are much more docile than their Northern relatives and attain lengths of 7–9 feet (2.1–2.7 m), while the overall average size is closer to 6 feet (1.8 m). Those from the southern end of their range in Peru tend to be darker in color. Amazon Basin specimens generally have an uninterrupted white dorsal line, whereas the white markings in specimens from Guyana and Surinam (known as "Guyana Shield" or "Northern" emerald tree boas) are quite variable. The snout scales in Amazon Basin specimens are also much smaller than in their Northern, Southern and Western counterparts found, for example, in Surinam, Venezuela, Bolivia, and French Guiana. Hybrid forms between the Northern Shield "Corallus caninus" and the Amazon Basin form are also known to exist.