Coitus of the longest duration in mammals occurs in mink and sable. Unlike coitus in other species, there is no "locking" of the genitals, but when intromission has once been achieved it is maintained for very long periods: several ejaculations can occur with rests between them. Timed matings of the sable have lasted for as long as 8 hours from the moment of original insertion until the time of withdrawal. One authority (Marshall's "Physiology of Reproduction") gives coitus in the mink, as in the ferret, as "prolonged" and usually lasting for 30 to 40 minutes - with a range of 20 minutes to 2 hours. Ovulation follows after a period of about 40 hours: if conception does not occur, the animal experiences a state of "pseudopregnancy."