Chester Rows east side of Northgate Street. Originally there were also Rows in Lower Bridge Street but these were blocked during the 17th and 18th centuries. As the ground floor buildings are usually lower than the street level, they are sometime known as "crypts". However, as the architectural historian Nikolaus Pevsner points out, this is not a strictly accurate description because the level of the floors of the buildings is a half-storey rather than a full-storey level below the street. Rows were built in the four main streets leading from Chester Cross, each of which originated during the settlement's early development. In
Whiskers to around 50 mm in (laboratory) rats, 30 mm in (laboratory) mice, and a slightly larger number of microvibrissae. Thus, an estimate for the total number of sensory nerve cells serving the mystacial vibrissal array on the face of a rat or mouse might be 25,000. Rats and mice are considered to be "whisker specialists", but marine mammals may make even greater investment in their vibrissal sensory system. Seal whiskers, which are similarly arrayed across the mystacial region, are each served by around 10 times as many nerve fibres as those in rats and mice, so that the total number