LINCOLNSHIRE FRESHWATER MITES. 



C. F. GEORGE, M.K.C.S.. 

 Kirtoii-in-Lindsey, JJticoliishire. 



Eulais Latr. This family has for the last seven years excited 

 great interest, and is still being- very closely studied in different 

 parts of the world. The nanie was g-iven by Latreille to a mite 

 described b}' ' MiiUer ' in 1776, under the name of Hydnichna 

 extendeiis (see ' Zoolog^ia' Danice prodromus,' pag-e igo, No. 

 2272), the specific name being- derived from the fact that when 

 the creature swims the hind leg's are extended backwards, and 

 not used tor swimming ; this is a characteristic of the whole 

 family. For a leng'th of time there was supposed to be only one 

 species. In 1837 Koch figured and described five. These were 

 not differentiated with sufficient clearness to be identified, and 

 were again supposed to be really the same creature. However, 

 in 1896, Koenike pointed out certain anatomical differences not 

 before observed, which excited so much interest, that in a short 

 time many new species were described b}' various observers. 

 Hence Piersig was able to describe no less than 35 species in 

 ' Das Tierreich ' (published in 1901), and since that time a con- 

 siderable number have been added to these. South Africa and 

 South America contributing. Indeed, this family is evidently to 

 be found in tolerable abundance all over the world, new species 

 frequently turning up, the eyes and their setting being the 

 portion chiefly figured, that being the part where so many and 

 such remarkable differences are to be found ; the palpi also in 

 some cases are useful as assisting in diagnosis. It seems rather 

 strange that, notwithstanding all these minute observations, and 

 skilled observers, no one excepting Koenike seems to have 

 figured the external sexual organs of the male. On looking- 

 over a few specimens preserved in fluid I found three differing 

 greatly from the rest in structure. These were evidently males, 

 there being a well-formed penis in the situation where in the 

 female there is a simple slit. This organ is of considerable size 

 and can be easily dissected from the mite. It differs consider- 

 ablv from the figures by Koenike, and from the male organ of 

 anv water mite I have yet examined. I sent one specimen to 

 Mr. Soar, who kindly drew from it the figures and ^■ 



accompanying this paper. He looked over his mounts o{ Eulais 

 and found two slides showing the penis, and from these he drew 

 the figures n, h, c. Figure a is a side view and gives a good 



Naturalist, 



