.* Weslagical Rept on’ the CNippeise' Land District Siam 
M's Mote than one half of ‘sive above series, supjiosed’ at first to be 
; + quite barren of all orgaiic forms, has already been arb fossils 
ce 24 eae and subsequent search will no doubt develop other 
“Tt is, moreo@gr, worthy of remark that the most fossil féroig = 
“ portion of F. 1 isnot its upper part, but beds which lie quite low ~ 
down, even seven to eight hundred feet beneath what was, Up. to jg 
this time, considered the limit of the fossiliferous strata-of the. — 
Mississippi valley. Yet these strata prove to be as densely’ ‘erowd- hal 
with organic relics as any of the most fossiliferous strata, a 
“the blue limestone of Ohio, Indiana, and Kentucky... The pro- 
. portion of genera and species, it is true, is not great, bit the bum- ag 
* _ ber of individuals is immense ; some slabs a are sO. cover éd_ with- 
‘shells, that it would be difficult to place the finger on a spot’ with-. 
out touching some of them. ‘The prevalent genera are Lingulas 
and Orbiculas ; yet associated with these -are some’ “ear as 
forms of crustaceans. The specimen figured on Pl. %, fig. 
the pygidium of a peculiar trilobite, armed with | eal ; 
_ projecting from its posterior margin. I obtained it in thin’b Zhe 
silico-calcareous layers near the “level of low water mark below i 
_ Mountain Island, in connection with. schistose gritstones. The 
* latter are charged with very perfect specimens of a sma fossil 
shell having a nacreous lustre closely allied to Obolus Apollinis a 4 
‘Eichwald, which are found by thousands in the inferior sand- _ 
4 stones of the protozoic strata of Russia. Associated with these - 
~ shells are’ also found remarkable compressed sub-conical bodies, — 
the nature of which I have not fully fetorinee but they. are, 
perhaps, spines of much larger trilobites than the one represented 
on Pl. 7, F. t. Yet these beds are identical Fak layers near low 
water at Mountain Island, entirely beneath a Lingula sandstone 
which, in all probability, is the western equivalent of the Lingula 
beds of the New York Potsdam sandstone, considered by most 
American geologists the oldest fossiliferous rock in - ye aoe 
States. The imbedded species of each seem the as. 
one can judge from mere casts. Ata little higher zeolosieal level, — 
between Prairie a Ja Crosse and Bad Axe, I obtained numerous — 
casts of Orthis in an impure, dark, flesh-colored, calcareous ‘rock, e 
associated with bueklers of a species of trilobite, which appears 
» be new. Ina similar rock, near the foot of La Grange moun- 
in, I also observed casts of Delthyris beneath green sandstone. Be 
le 
~~“ About the same geological ry oly ah an argillo-caleareous 
* ‘rock, near the level of the head of Lake St. Croix, is avery large _ 
“a species of Asaphus. the buckler and ite Me of whichis — 
figured on Pl. 7, Fig. 2 and 3. Finally, at Marine Mills, ten— 
miles ses Lake St. Croix, only eighteen or twenty feet higher, 
»viz.: in F, 1 e, ina soft gritstone, are abundance o bucklers and — 
based eeeaeoe of small trilobites, possessing some @ 
