90 Marl of New Jersey. 
of the bone, and lying on one side even over the ribs. Part of the 
bones are removed to show the trachea. 
Fig. 2. Showing less developement, being from a younger bird. 
Fig. 3. Sternum of a cygnet of the first year, giving a mere 
swelling on the internal surface of the bone. 
Plate I].—Fig. 1. Side view of the sternum and trachea of the 
Swan. A. The keel. B. Flat posterior part of the bone. C. C. Tra- 
chea. D.D. Muscles of voice. E. Bone of divarication or larynx. 
F. The delicate semicircular bone with the outer membrane attached, 
to protect the inner tube leading to the bronchie. G. Bronchie. 
H. H. Os fureatorium. I. Posterior horizontal chamber. 
Fig, 2. Front view of the same part, the anterior portion of the tra- 
chea turned aside to show the inner ascending part of it—the muscles 
of voice, and the tendinous membrane by which both are supported. 
Art. V.—On the analogy which exists between the Marl of New 
Jersey, &c. and the Chalk formation of Europe. | 
Letter from §. G. Morton, M.D. to the Editor, dated Philadelphia, Feb. 14, 1832. 
PROFESSOR SILLIMAN. 
Dear Sir—Constant engagements, chiefly of a professional na- 
ture, have, for nearly two years past, prevented my taking an active 
part in geological inquiries; at the same time I can assure you, that 
my interest in the subject has in no degree diminished, which must be 
my apology if this communication should appear too long or too minute. 
Since.the publication, in your valuable Journal, of my “ Synopsis 
of the Organic Remains of the Ferruginous Sand Formation of the 
U. S.”*—I have waited with patience for the judgment of European 
geologists upon the opinions therein advanced ; and have at length the 
gratification to observe, that those opinions have received the support 
and corroboration which I had little doubt would be awarded to them. 
In a letter recently addressed to me by Prof. Alex. Brongniart,: 
are contained the following observations ; to which I shall subjoin an 
extract from the report alluded to by this eminent geologist. 
“T have been struck with the analogy,” says M. Brongniart, “ which 
exists between the American beds, referred by you to the chalk se- 
ries, and certain European deposits belonging to the same Pelagic . 
group. I have communicated this curious fact to the Royal Acade- 
my of Sciences, in a Report lately submitted to that body in relation 
* Volumes XVII and XVIII. 
