PLATE V. 



FIG. I. 



MONOCULUS CONCH ACEUS. 



Aptera. 



Without wings. 



Generic Character. 



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



Specific Character. 



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

 which it puts forth a number of capillary antennas, which it retraces 

 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 objects, 

 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 ; 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 infect in the drop of 

 the fluid from the lens, and thereby the lens may approach the object 

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

 immerged in the water, and entirely obftruct the fight. 



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

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

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

 microfcope. 



It breaks from the egg perfectly formed, but very minute and trans- 

 parent; this is therefore the beft time to difeover its ftructure, and 

 from one in this ftate we have taken our figure. 



S By 



