essential parts of the head, generated with the brain itself. He notes that the bones scale proportional to the size of the fish, and are most easily discovered in the heads of Spinose fish. Klein identifies three pairs of bones to which he attributes the sense of hearing, and he takes to correspond to the Incus, Malleus and Stapes of other animals. The first are the two largest, which he explains are easily found; the other two pairs, he explains, are small, difficult to find, enveloped in distinct fine membranes. Klein believed one could determine the age of fish by analysing the number and thickness of the Laminae and fibres of these bones. The bone to which Klein was referring, now called the otolith, acquires a growth ring every day for at least the first six months of its life. Klein inquiries into the nature of the passages by which vibrations produce a sense of hearing. He inspects the head of a Pike fish and observes several holes with bristles which lead to the auditory bones. He later dissected a Sturgeon fish and traced the auditory duct to the membrane in which the three bones are placed. Klein concludes that fishes do indeed have hearing organs and passages, communicated to through slight vibrations, though these passages are not easily demonstrable in many species. He observes that the auditory organs of cetaceous, cartilaginous and spinose fish differ from one another in structure and substance. The auditory organs of cetaceous fish are bony, while they are more fragile for cartilaginous fishes, he explains. He adds that water does not act as an impediment to hearing, but rather is the “intermedium” by which sound is communicated. Honours Klein had been awarded the membership of several scientific societies, including the Royal Society in London, the St. Petersburg Academy, and the Danzig Research Society. The name of the genus Kleinia was given to the plant family of Compositae (Asteraceae) by Linnaeus in honour of Klein's works. He was described as the most important natural philosopher of his century by Professor Johann Daniel Titius. Criticism Although well respected by his colleagues, Klein was nonetheless accused by some contemporaries of being unscientific, alleging that he based his beliefs on the hearsay and the claims of ‘credulous’ people. The 1760 edition of the Philosophical Transactions of the Royal Society of London published a letter by 18th Century botanist