Evolution of the cochlea about 7 mm long. Like in lepidosaurs and archosaurs, it contains a lagena, a vestibular sensory epithelium, at its tip. Only in therian mammals (marsupials and placentals) is the cochlea truly coiled 1.5 to 3.5 times. Whereas in monotremes there are many rows of both inner and outer hair cells in the organ of Corti, in therian (marsupial and placental) mammals the number of inner hair-cell rows is one, and there are generally only three rows of outer hair cells. Amphibians have unique inner ear structures. There are two sensory papillae involved in hearing, the basilar (higher frequency) and amphibian
Jock Stirrup plans could be afforded over the coming years. The planning for the invasion of Iraq required new equipment and Stirrup became increasingly involved in planning for urgent operational requirements. A particular difficulty faced by Stirrup was the need to place equipment orders with industry before the Government was prepared to publicly commit to the action. Stirrup briefed ministers on this point but was prevented from placing the orders according to his desired timescale. In the end some critical items such as body armour, boots and desert clothing were not available to all the personnel who needed them when they deployed.