[ 15. ] 
oo ae as Me 
Bo lv Gi. ds 
MONOCULUS CONCHACEUS. 
APTERA? | 
GENERIC CHARACTER. 
Legs from four to eight, formed for fwimming, and very long: 
body covered by a fhell divided into fegments: Antenne either 
four, two, or none; eyes one, or two, approximate and fixed in the 
fhell: feelers four, and in continual motion when {wimming :_ pofte- 
rior ones very {mall and hooked. 
SPECIFIC CHARACTER. 
Shells ovate and downy. 
To acquire a proper knowledge of the formation of this minute in- 
fe&t, it is neceflary to ufe a microfcope with a glafs ftage for objeéts, 
or rather fuch as admit of nicely adjufting a tale as occafion may re- 
quire: the infeét to be taken from the water with a camel-hair pencil, 
and carefully placed on the talc; after which ic may be examined by a 
magnifier of 35 of an inch focus; but in proceeding to a deeper power, 
let the talc be turned the upper furface with the infeét 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 obftruét the fight. 
-In the adult flate, 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 vifible by the 
microfcope. 
It 
