[Frankfurt am Main, 1969]. Handwritten in ink on rectos of 14 uniform, loose, ruled leaves (20.8 x 14.8 cm), and in pencil one one very large oblong (29.7 x 42.0 cm) graph paper sheet.

The original manuscript of Robert Mertens's work titled Zur Synonymie und Variabilität der Würfelnatter (Natrix tessellata ). This is a non-venomous snake with a wide, Eurasian distribution. Published published in Senckenbergiana Biologia 50, pp. 125-131. Professor Robert Mertens (1894-1975) was one of Germany's foremost zoologists and herpetologists during the 20th century. In 1919, after completing his studies, he became first assistant of the Senckenberg Museum in Frankfurt am Main. In 1920 he became curator for herpetology, and in 1934 head of the zoological section. Finally, in 1947 he became director. Mertens was not only one of the foremost herpetologists of his time, but also one of the most productive of all time. This manuscript reveals some of his methodology. First he carefully wrote a draft in blue ink, usually with few original additions and corrections, the he made new corrctions and additions in pencil, and - for emphasis - red crayon. The pencilled table describes up to 11 characters of 15 specimens carefully measured by Mertens. All leaves in very good condition. Adler I, pp. 98-99; Schirner, 720.