Descriptions of two species of Tralobites. 139 
40. What are the directions of the joints, heads, or natural divis- 
tons of the granite,. killas, elvan, or other rocks, and do such joints 
agree, or not, with the general directions of the lodes and cross 
courses ? 
R. W. Fox, takes the liberty to submit the accompanying ques- 
_tions to practical miners, hoping that they will kindly reply to them, 
or to some of them, and add such general observations on the subject 
of lodes as may appear to be worthy of notice. He hopes that it 
will not be inconvenient to them to furnish him with the desired in- 
formation without much delay ; it will be quite sufficient merely to 
refer to the numbers marked against each question. 
In any cases in which plans and sections of lodes and cross courses 
have been made, rough sketches of them will be much valued. 
Arr. XIL.— Descriptions of two species of Trilobites, belonging 
to the genus Parapoxipes ; by Mr. James Hau, Corresponding 
Member of the Yale Nat. Hist. Society. 
Read before the Yale Nat. Hist. Society, March 21, 1837. 
Tue following remarks and the accompanying figures are offered 
to this Society as illustrations of two species of fossil trilobites, which 
hitherto have been imperfectly and in many respects incorrectly de- 
scribed. ‘The buckler of these species was first observed by Prof. 
Eaton, and described as the abdomen and tail of an unknown trilobite, 
which he named in honor of the distinguished Brongniart, Brongni- 
artia Carcinoidea. ‘The buckler is often found in great numbers, 
and almost invariably separated from the abdomen. This circum- 
stance and the peculiar appearance of the fossil, led Prof. Eaton to 
the above conclusion respecting its nature, which, I believe, was 
sanctioned by Brongniart. Similar imperfect specimens of the two 
species were afterwards described by Prof. Green, (with the same 
views as to the nature of the fossil,) under the new designation 7'7- 
arthrus Beckii. More recently Dr. Harlan has corrected the prin- 
cipal error of preceding authors, (that of considering the buckler as 
the abdomen and tail,) and has described the specimens as constitu- 
ting two species of the genus Paradoxides. About two years since, 
while engaged in investigating specimens of unusual perfection from 
several localities, | observed some inaccuracies and omissions in the 
