[...] Nova auris internae delineatio

4to. [4] leaves. Collation: A4. Printer's device on title page (an eagle with spread wings above a vase containing three lilies supported by a hand coming out of the clouds, in a figurative frame). Woodcut initial and headpiece. On l. A3r full-page engraving by Giacomo Pecini (c. 1617-1669) containing six numbered figures. Some light foxing, traces of folding as the pamphlet was presumably sent as a letter, a very good, wide-margined copy.
 
EXCEEDINGLY RARE ORIGINAL EDITION (first issue) of the most accurate description of the ear up to its time.
The work, sent as a letter - the dedication is dated Venice, May 10, 1645 - to the a Danish physician, mathematician, and theologian Thomas Bartholin (1616-1680), became immediately sought-after and rare. Its fame and importance are due to the engraved plate containing six figures that offer an extremely accurate and analytical description of the middle and inner ear. Folli describes some structures of the hearing organ never previously observed and, among the many remarkable morphological details showed in the plate and described in the pamphlet, of particular importance is the depiction in figure 2 (Figura Secunda) of the long process of the malleus, also called “Folli or Follian process”, that is a slender spur running anteriorly from the neck of the malleus toward the membrane of the tympanum. Folli also identifies the lenticular process of the anvil which he calls “os globulus”, whose discovery is attributed to S. de Le Boë. However, Folli mistakenly considers it as an independent bone. Figure 3 (Figura Tertia) gives “the first illustration of the so-called fourth ossicle (stapedis, osseus globulus); it appears to be an extension of the head of the stapes to which it is attached” (C.D. O'Malley & Edwin Clarke, The discovery of the auditory ossicles, in: “Bulletin of the history of medicine”, September-October 1961, vol. 35, no. 5, p. 441 and fig. 5).
The fact that the work is addressed to Bartholin is a clear indication of the esteem and friendship that existed between the two; Folli went often to Padua, where Bartholin resided, both to discuss with him the development of his research and to make practical demonstrations of anatomy. In Bartholin's correspondence (Epistolarium medicinalium a doctis vel ad doctos scriptarum centuriae, Hagae Comitum, 1740, cent. I, epist. LXXII, p. 251), besides the Nova auris there is another letter written by Folli, dated 4 November 1644 and titled Observationes quaedam anatomicae, which contains several anatomical observations on the skin, peritoneum, cardiac ventricular ulcerations, and intestinal worms. Bartholin also contributed to the circulation of the Nova auris internae delineatio as is shown in the copy now preserved at the Augsburg State Library which bears his dedication to the German physician Lucas Schrockius (Lucas von Schröck, 1620-1689).
“Caecilius Folius […] is known to have written three works, but the single one of these which brought him such renown as he ever enjoyed was his ‘New Delineation of the Internal Ear,' an opuscule of six fairly well executed plates with a brief explanatory text for each, and said to have been the most nearly accurate description of the inner ear up to its time. More than a hundred years later Antoine Portal said of it, ‘This is the manner in which judicious and perspicuous spirits know how to describe in a few words the most complicated objects and how to explain the most interesting discoveries. If everyone had followed the method of Folius there would be fewer books but just as much positive knowledge. It has been said that Vesling used Folius' drawings and description in his own Syntagma Anatomicum, published from Padua in 1641, a date at which Folius would be twenty-six years of age. But Vesling nowhere acknowledged any debt, and the name of Folius is conspicuously absent from the rather long list of anatomists mentioned in Vesling's Syntagma” (G. Kasten Tallmadge, Caecilius Folius on the c