PLATE V. 

 FIG. I. 



MONOCULUS CONCHACEUS. 



Aptera. 



Without wings. 



Generic Character. 



Body covered with a cruft or fliell. Feet made for fwimming. 



Specific Character. 



Inclofed in a bivalve, afh -coloured fliell, from the aperture of 

 which it puts forth a number of capillary antennae, which it retrads 

 when taken out of the water. 



To acquire a proper knowledge of the formation of this minute in- 

 fect, it is neceflary to ufe a microfcope with a glafs ftage for obje6^SJ^ 

 or rather fuch as admit of nicely adjufting a talc as occafion may re- 

 quire : the infect to be taken from the water with a camel-hair pencil, 

 and carefully placed on the talc j after which it may be examined by a 

 magnifier of i of an inch focus ; but in proceeding to a deeper power, 

 let the talc be turned the upper furface with the infe6l in the drop of 

 the fluid from the lens, and thereby the lens may approach the obje£l 

 to its proper focus ; without this caution the lens would be frequently 

 immerged in the water, and entirely obflrudl the fight. 



In the adult ftate, the opacity of the bivalve fhell, its externaF co- 

 vering, fo entirely obfcures the internal motion, that nothing, except 

 the filaments it throws from the aperture or opening, is vifible by the 

 microfcope. 



It breaks from the egg perfe£tly formed, but very minute and tranf- 

 parent; this is therefore the beft time to difcover its ftrucliire, and « 

 from one in this ftate we have taken our figure.- 



5 By 



