152 Muller on the Structure of the Eyes 



In confirmation of the above, it may be added, that other 

 veins of quicksilver, appearing, by the analysis of Professor Del 

 llio, to afford ores worth working, have recently been disco- 

 vered in Mexico. Analyses of two specimens of the ore may 

 be seen in the Philosophical Magazine for August, 1828. 



The pits (shafts) and adits, by the aid of which the water is 

 carried off from the mines, are then described. 



These, with a chapter describing the operations of the 

 mint of Mexico (vol. ii. p. 233), a vocabulary of mining terms 

 (vol. ii. p. 320), and an enumeration of the mining districts of 

 New Spain (vol. ii. p. 332), are the principal matters falling 

 under the second head, which are treated by the author at 

 length, and with these we shall conclude the present analysis ; 

 passing over the legal department of the subject, which, 

 although forming the bulk of the work, might, we apprehend, 

 be less interesting to the readers of this Journal. 



Anatomische Untersuchungen uber den Bau der Augen bei 

 den Insekten und Crustaceen vom Dr. J. Muller zu Bonn. 

 Mekel's Archiv fiir Anatomic und Physiologic. 1829. 

 (Anatomical Investigations of the Structure of the Eyes in 

 Insects and Crustacea, by Dr. J. Muller, &c. &c.) 



nnHE original observations of Dr. Muller, contained in his 

 -*- * Beitrage zur vergleichenden Physiologic des Gesicht- 

 sinnes, Leipzig, 1826," of which the present paper is a conti- 

 nuation, and which have subsequently been confirmed by G. 

 Treviranus, Huschke, and Straus Durckheim, have hitherto 

 been unnoticed in this country. They are of interest, how- 

 ever, not only as furnishing more correct ideas of the structure 

 and character of the eyes of Insects and Crustacea than those 

 generally received, but also as serving to remove the apparent 

 anomalies by which they were supposed to be separated from 

 the corresponding organs in vertebral animals. 



It may not be superfluous to state, that, according to the 

 usually admitted opinions, the structure of these organs, whe- 

 ther simple, conglomerate, or compound, is essentially similar; 

 consisting in pyramidal prolongations of the optic nerve, covered 

 by a uniform stratum of black pigment, and externally by a 

 transparent cornea ; the existence of a crystalline or vitreous 

 humour being expressly denied. Such an organization, whilst 

 it presents no analogy with that of the higher animals, places 



