11. — British Enchijtr/i'ids. 

 By The Eev. Hilderic Friend, F.L.S., F.K.M.S. 



{Read November 15, 1911.) 

 III. 'The Genus Fridericia. 



The genus Fridericia is by far the largest in the family of Enchy- 

 trieids. It was founded by Micliaelsen in 1889, in order to bring 

 together a number of species which had previously been placed in 

 such genera as Enchytrwus, Neoenclnjtrivus, Arclticnchytnvus, and 

 the like. All the species are small, ranging between 3 and 30 mm., 

 with the exception of one British species {Fridericia magna Friend), 

 which may reach a length of 40 mm. All need the Microscope for 

 their examination and determination, and the field is a difficult one, 

 owing to the number of species whose characters are similar, and 

 the want of a concise and systematic diagnosis. But every year 

 finds us emerging from chaos, and the fuller study of large numbers 

 of species and specimens is enabling the systematist better to 

 understand which are the points most to be relied upon in the 

 animals' structure. 



With the exception of the species already mentioned, in which 

 the blood is red, all the Fridcricias have colourless, or at most pale 

 yellow blood. Consequently they usually present a white or grey 

 appearance, except when the intestine is filled with humus or dark- 

 coloured food. Specimens are to be found in almost every conceivable 

 locality, but their favourite haunts in England are the ditches 

 where leaves, twigs, and vegetable debris generally, are decaying ; 

 or in earth which contains a large amount of humus. They are 

 often associated with various species of earthworms, and seem to 

 act as forerunners in many cases, preparing the way for the larger 

 species. A kind of messmatism may be said to exist in some in- 

 stances, for I have frequently found that when large stones have 

 lain for a time upon a grass plot, causing the grass to decay, certain 

 species of Fridericia have been present in the dead material along 

 with Lumhricus ruhcllus Hoffm. 



One of tbe principal differences between Fridericia and the 

 other Enchytneids lies in the setae, which are usually of different 

 sizes in the anterior portion of the body, the innermost setae in 

 each bundle bein" shorter than the outermost. But since a large 

 number of Fridcricias possess only two setee in each bundle, and 

 these are of equal length, some other generic characters have to be 



