S72 Observations on the Diluvial Gravel 



cia, &c. The lines aub and cud mark the boundaries of 

 elliptical eyes with the summits placed laterally. The lines 

 uo, no, q 6, p 6, are the sectors of eyes having the shape of 

 segments of ellipsoids, as a uo, ayn, 6 c u. The sectors in 

 none of these instances converge in front, and an object 

 placed between the two eyes can never be seen simultaneously 

 by both. No example of convergence of the two eyes ante- 

 riorly has yet apparently been noticed. When the position of 

 the eyes is rather anterior than lateral, as in many dipterous 

 insects, and, among the Hemiptera, in the genera Naucoris 

 and Notonecta, these organs, although very close to each 

 other, form segments of only one and the same sphere. 

 There is, also, never any collision between the different fields 

 of vision when there are more than two compound eyes. 



Crabs, and a few others of the Crustacea only, have mov- 

 able eyes fixed upon pedicles ; nevertheless, even these eyes 

 never vary their degree of divergence, their movements being 

 combined and in unison, as is the case with the eyes of verte- 

 bra ted animals. In the Crustacea with long bodies, the eyes 

 are very near to, and but little divergent from, each other : 

 the contrary is observed in those whose bodies are very broad. 



I am. Sir, &c. 

 Newkall Street, Birmingham, Jan, 19. 1831. G, P. 



Art. XIV. Observations on the Diluvial Gravel in the Neighbour' 

 hood of Birmingham, By Frederick Jukes, Esq. 



Sir, 

 The late excavations for the line of a new canal between 

 this town and Wolverhampton having been made through 

 a very deep bed of sand and gravel in the neighbourhood of 

 Smethwick, some interesting phenomena in. diluvian speci- 

 mens have presented themselves. This deposit is not only 

 remarkable for the number and variety of organic remains to 

 be found in it, but also from the vast accumulation of detached 

 rocks of almost every description. The circumstance of large 

 rounded blocks of basalt and ironstone being so abundantly 

 dispersed throughout this bed, may be ascribed to the disin- 

 tegration of the neighbouring trap hills of Rowley and the 

 ironstone of Coseley Hill *, both within the distance of a few 



* The section of this hill, which is now in progress for the passage of 

 the canal, presents a good example of the disturbing force to which the 

 vegetables of the coal formation have been subjected at the time of their 

 deposition. 



