KNOWLEDGE OF THE HYDKACHXIDAE. 285 



swimming-setae; palpi simple, subulate, profusely setose; genital 

 plates symmetrically elliptical, each plate bearing three serially 

 and meclianly disposed ovate tubercles ; eyes constituting but one 

 distinct pair. Type : L. insignis Neuman. 



But a single species of this form, the Lebertia insignis of 

 Neuman, has been so far discovered, and this cannot yet be 

 recorded as a denizen of this countr3\ While the coalesced con- 

 dition of the epimera and pattern of the genital places predicate 

 its close affinity with the two preceding genera, the distinctly 

 developed median suture separating the epimera of the right and. 

 left divisions of the bodv would seem to indicate a structural 

 development towards those forms in which these basal elements 

 of the ambulatory appendages are completely isolated. 



Genus 4. Mideopsis Neuman. 



Body suborbicular, depressed : cuticle indurated, granular, with 

 an impressed subcircular dorsal area, a fascicle of two or three 

 antennary setae developed on each side of the anterior border 

 and other isolated setae upon the peripheral border and dorsal 

 surface ; epimera forming two distinct groups through the coales- 

 cence of the right- and left-hand elements respectively ; swimming- 

 hairs developed upon the two posterior pairs of legs, all four 

 pairs terminating in a double claw ; palpi subulate, extensively 

 setose, the fourth joint with an inferiorly developed tooth -like 

 projection; genital plates evenly ovate, with three internal 

 lineally disposed tubercles on either side and a broad granulate 

 non-tuberculate border ; eyes forming but a single distinct 

 pair; ova and larvae undescribed. Type: Mideopsis depressa 

 Neuman. 



A single example of the above-named type-form of this genus 

 was obtained by the writer from the lake in Kew Gardens 

 Park in 1881. Contrary to Neuman's intimation in his diagnosis 

 that the species possessed no dorsal stigmata, the writer has 

 recognised distinctly in the example captured at Kew and pre- 

 served in glycerine the presence of four pairs of such glandular 

 orifices, each accompanied by a tactile seta, within the area 

 circumscribed by the dorsal impression, and, in addition to these,, 

 seven pairs of marginal setae, in place of the four only as de- 



