L982) 
PL ADE. 
ELG. 4. 
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 
thell : feelers four, and in continual motion when fwimming ;_pofte- 
"lr ones very {mall and hooked. | 
SPECIFIC CHARACTER. 
Shells ovate and downy. 
Cee ae nn naan none nenenenseemneneaenmmneaeen ; 
To acquire a proper knowledge of the formation of this minute in- 
» itis neceflary to ufe a microfcope with a glafs ftage for objeéts, 
°F rather fuch as admit of nicely adjufting a tale as occafion may re- 
(Wire: the infe& 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 
ga of '5 of an inch focus; but in proceeding toa deeper power, 
ey Rook be turned the upper furface with the infe& in the drop of _ 
a uid from the lens, and thereby the lens may approach the objeét 
im “pe aad focus; without this caution the lens would be frequently 
merged in the water, and entirely obftruét the fight. 
- the adult ftate,. the opacity of the bivalve fhell, its external co- 
r : : : : 
‘ mo fo entirely obfcures the internal motion, that nothing, except 
e . : \ 7 “a 
Re: laments it throws from the aperture or opening, is vilible by the 
Mcrofcope, 
It 
