42 Observations by T. A. Conrad 
ous genera may be collected. We observe here several of the com- 
mon bivalves which live as far north as Massachusetts. Beds of 
Modiola demissa are planted about the Mangrove roots ; Cardium 
Mortoni is profusely scattered over the flat muddy shore ; Osteo- 
desma hyalina is not uncommon; Pecten concentricus, ‘Mhomid 
ephippium, Balanus ovularis staid some other northern shells 
abound here ; but the greater proportion of species are limited to 
ais south coasts of the Union. Along the water’s margin at 
_ low tide, the beautiful little Marginella conoidalis crawls slowly 
upon the surface of the mud. It is accompanied by a far more 
abundant univalve, Nassa vilrx of Say, which appears in constant 
motion, like its neighbor. Upon the flat muddy shore, which 
has a great breadth when the tide is out, live great numbers of 
that beautiful coronated univalve, named Murex corona by Lin- 
nus, which also seems yery partial to oyster beds, and preys 
upon the animal of Ostrea virginiana. I found here a rare variety 
of the shell with a double row of spines. The character of this 
species seemed to me such as would place it in the genus Melon- 
gena of Sowerby ; most certainly it is not generically the same 
with Fusus, Pyrula, or Murex to all 6f which it has been referred 
by authors. The most noticeable shells on these flats, are the 
gigantic Fasciolaria trapezium, Fulgur perversus, and F. 
On the bars, nearly exposed at low tide, are beds of spinous Pinnls 
and a gigantic species of Venus,* (V. Morténi ,) the shell of which 
weighs four pounds. Many specimens of Limulus polyphemus 
are scattered along shore. ‘This crustacean has a wide range, a8 
it inhabits nearly the whole Atlantic coast of the Union. On the 
grass, bushes and mangrove trees, as high as one can reach, great 
numbers of the elegant Littorina angulifera live and feed upon 
the leaves. Many of the shells of the bay shores seem to be 
confined to the bay, as I never observed them on the sea beaches 
of the Keys, and yet some of these species inhabit Long Island 
Sound and the waters about Newport and Boston. It would be 
‘interesting could we discover which locality was first colonized 
2 — ences, but we know not any clue to information - i 
ra stdlescondta Tampa bay is sandy and barren, filled swith 
th oti hk roots uae — and not worth the a 
i me it ‘ae f Fl id 
