Several terms are found which have regard to the nature of services. Agricultural work was the most common and burdensome expression of economical subjection. Peasants who have to perform such services in kind instead of paying rents for them are called _operarii_[275]. Another designation which may be found everywhere is _consuetudinarii_ or _custumarii_[276]. It points to customary services, which the people were bound to perform. When such tenants are opposed to the villains, they are probably free men holding in villainage by customary work[277]. As the name does not give any indication as to the importance of the holding a qualification is sometimes added to it, which determines the size of the tenement[278]. In many manors we find a group of tenants, possessed of small plots of land for the service of following the demesne ploughs. These are called _akermanni_ or _carucarii_[279], are mostly selected among the customary holders, and enjoy an immunity from ordinary work as long as they have to perform their special duty[280]. On some occasions the records mention _gersumarii_, that is peasants who pay a _gersuma_, a fine for marrying their daughters[281]. This payment being considered as the badge of personal serfdom, the class must have consisted of men personally unfree. [Terms to indicate the size of the holding.] Those names remain to be noticed which reflect the size of the holding. In one of the manors belonging to St. Paul's Cathedral in London we find _hidarii_[282]. This does not mean that every tenant held a whole hide. On the contrary, they have each only a part of the hide, but their plots are reckoned up into hides, and the services due from the whole hide are stated. _Virgatarius_[283] is of very common occurrence, because the virgate was considered as the normal holding of a peasant. It is curious that in consequence the virgate is sometimes called simply _terra_, and holders of virgates--_yerdlings_[284]. Peasants possessed of half virgates are _halfyerdlings_ accordingly. The expressions 'a full villain[285]' and 'half a villain' must be understood in the same sense. They have nothing to do with rank, but aim merely at the size of the farm and the quantity of services and rents. _Ferlingseti_ are to be met with now and then in connexion with the _ferling_ or _ferdel_, the fourth part of a virgate[286].