186'-] 321 [Biighani. 



The Avadiii<j; and swimming l)irds have not been inchuled in this 

 comparison; they usually breed in inaccessible or secluded places, or 

 in high nortliern latitudes, or in such multitudes together that theu' 

 very numbers afford a sufficient protection, or render the losses they 

 sustain from carnivorous enemies of comparatively little consequence 

 in the preservation of the speci(;s; they are, moreover, usually not 

 bright, aufl the eggs and females are generally colored like tlie sur- 

 roundings of the nests. 



Another interesting coincidence, if not showing the relation of cause 

 and effect, is tliat in the concealed or concealing nests, the eo-trs, as a 

 general rule, are white — as in tliose of the owls, swallows, kingfishers, 

 woodiDCckers, humming birds, quails, and doves. 



Mr. Wallace, being a Darwinian, would explain this curious and 

 unexpected connection between the manner of a bird's nesting and 

 the color of the female plumage, by the laws of variation and heredi- 

 tary transmission, and the cumulative effect of natural selection or 

 survival of the strongest, and as illustrating how large a part the need 

 of protection has played in producing many of the most striking 

 peculiarities in the animal kingdom. 



Mr. W. T. Biighain read a paper upon the form of vol- 

 canic craters as influenced by a suj^posed line of fracture in 

 the earth's crust. 



All large craters are oval or elliptical, and it is exceedingly rare to 

 find one of circular form. It is inferred that the elongated shape is due 

 to their formation over a longitudinal fissure. Where this crack is 

 widest the larger portion of the crater will be found. On examining 

 the direction of some of the principal lava craters a curious fact is 

 observed; they are generally at right angles to the general line of 

 volcanic vents. Thus the crater of Antuco, one of the loftiest of the 

 southern Andean volcanoes, has its major axis in an east and west line, 

 while the Aiides range nearly north and south. Gelunggung in Java, 

 has a huge crater opened towards the north, while the Javan line is an 

 east and west one. The same is true of Orizaba in the Mexican chain 

 of the 19th parallel. Santorini and the other islands of the volcanic 

 band of the CJrecian Archipelago, which trend north-west and south- 

 cast, have their major axes at right angles to this general direction. So 

 is it with Vesuvius, with ^tna, and Teneriffe, and, so far as I am aware, 

 with all known volcanoes. Unfortunately, the information we possess 

 of the direction of the elliptical craters is very scanty, as attention 

 has not been turned to this matter. When sufficient data shall have 

 been obtained I believe the direction of the major axis will determine 

 the direction of volcanic trains and thus of the rents in the earth's 



PROCEEDINGS B. S. JJ. H. — VOL. XI. 21 APRIL, 1868. 



