To answer the second half of your question - Glitsch didn't work from first hand specimens because he didn't have them. The lizards in question come from North and South America, Africa, Australia and Java so he wasn't going to travel that far for one engraving when he had sketches to work from. Unfortunately Haeckel, his source for the sketches, never travelled that far either and there is evidence that he worked (in part at least) from other peoples' work rather than from specimens.