OF GAMASID MITES FOUND ON RATS. 



123 



Laelaps echidninus, Berlese (figs. 3, 4). 



Q . Body oval in shape. Almost the entire dorsal surface is covered by the 

 scutum, but a marginal strip of soft skin is left unprotected. Hairs on scutum 

 long, fine and fairly numerous. Ventral plates with much finer hairs than 

 in L. agilis, C. L. Koch. Per itr erne long, its anterior end being situated 

 opposite (or a little in front of) the coxa of the first leg. Coxa of first 

 leg furnished posteriorly with a strong seta, of moderate length, and also with a 

 stout and rather blunt little thorn. Second and third coxae each with a similar 

 thorn on their posterior surfaces. Fourth coxa with a smaller and more slender 

 thorn (spine). The narrow central strip o£ the ventral surface of the capitulum 



S== *VJ / ) / ;/ 



Fig. 3. — Laelaps echidninus, Berlese, ventral view of female. 



is armed throughout its length with minute denticles. Movable finger of 

 chelicera with two little teeth, which are placed close together ; the distal end of 

 this finger is slightly curved, Immovable finger with a single minute tooth. 

 (For the shape of the seta of the immovable finger see fig. 4). Colour brownish. 

 Length of body 1*1 mm. 



Material. Numerous specimens found by the author and his brother 

 {Dr. L. F. Hirst) on rats (Mus norvcgims) from Barking Creek and other 

 specimens captured on rats taken at Tilbury Docks {Dr. Willoughby). We 

 are indebted to Dr. Herbert Williams (principal Medical Officer of Health 

 for the Port of London) for his kindness in forwarding the Tilbury specimens to 

 the Museum. Also specimens taken on Mus norvegicus in the United States 



