C. terrificus ranges from Arizona to Argentina, and is the only species of Rattle-Snake in South America. It differs from the others by having a pair of prefrontal shields behind the pair of internasals.

INDEX

Every reference is to the page: words in italics are names of genera or species; figures in italics indicate that the reference relates to systematic position; figures in thick type refer to an illustration; f. = and in following page or pages; n. = note.

Abdominal armour, of Cricotus, [287];

of Microsauri, [289];

of Prosauri, [290]

Abdominal ribs, of Rhynchocephali, [292], [298];

of Dinosauria, [414];

of Megalosaurus, [421]

Aberrant scaling of Lacertilia, [495]