1880. | .  Zoblogy. 213 
All the parts thus far described except the pigment layer, are 
moulted with the rest of the crust, and the large long slender 
cones can be easily seen by viewing a piece of the cast-off eye; 
the solid cones being seen projecting from the inner surface of 
the cast-off cornea. 
The internal structure of the eye is very simple. There are no 
cones and no rods, but a branch of the optic nerve impinges 
directly upon the end of the solid chitinous cone, as determined 
to settle. Are they crystalline lens or only analogous organs? 
Can the horse-shoe crab distinguish objects? We doubt if its eyes 
enable it to more than distinguish between the light and darkness. 
Since the above remarks were put in type, we have seen Grena- 
cher’s great work onthe eyes of Arthropoda. He regards the 
conical chitinous minnie-ball-like bodies as corneal lenses. He 
_ Goes not describe the simple eye, which is a close repetition of 
one of the corneal lenses of the compound eye of the same ani- 
mal, except that the lens is shorter and with the end much more 
obtuse.—A. S. Packard, Fr. 
ADVENT OF PASSER DOMESTICUS IN NorTH CArOLINA.—The 
following letter is published in the belief that it is desirable to 
preserve records of the spread of this bird in this country —Zi/iott 
Coues, Washington, D. C. 
: Darras, N. C., Nov. 30, 1879. 
Dr. Elliott Coues. 
Yours, &c., PauL B. BARRINGER, M. D. co 
~ THE STRUCTURE of THE TRACHEÆ AND THE “PERITI 
 CircuLaTIoN ” IN Insecrs.—Under this title M. Jules M 
x. l L Se 
