440 Mr. E. Blyth on the Genus Pyrrhula. 



caused by the action of the sea and weather on the soft sub- 

 stratum, thus bringing into eifect the law of gravitation. No 

 doubt the island will continue to diminish, until at length it 

 will disappear beneath the waves from which it sprung, — the 

 fate of an adjacent island now covered with 15 feet of water, and 

 known to the fishermen as the "sunken Filfla." On Filfla is 

 found a tolerable supply of water, slightly brackish, but suffi- 

 ciently sweet to be eagerly sought after by the thirsty fishermen, 

 who resort there in the heat of the day to take their siesta. 

 The water trickles from the side of the rock, and in one place is 

 collected in a large earthenware basin left by the fishermen for 

 this purpose under the shade of a reclining rock, where even in 

 the height of summer it issues cool and limpid. The reason of 

 this is evident. The water is absorbed in the rainy season by 

 the superlying limestone, and permeates slowly through it, as if 

 through a dripstone, until it comes upon the impervious clay, 

 when it is turned off in a horizontal direction. A thick stalac- 

 titic crust has formed on the face of the rock, rising to the 

 height of many feet. An enthusiastic collector of natural 

 curiosities of my acquaintance was once nearly paying dear for 

 attempting to gratify his wish of carrying away a piece of this 

 incrustation. Applying his geologist^s hammer to it, an immense 

 slab of stalactite was dislodged at the blow. Fortunately, he was 

 enabled by a rapid and vigorous leap to escape being crushed by 

 the falling mass. A corresponding depression to that of Filfla, 

 but to a still greater depth in some places, has occurred on the 

 Maltese coast opposite. This downthrow may be traced for 

 several miles along the line of coast, and serves to show the 

 connexion that doubtless once existed between the mainland and 

 the outlying Filfla rock. 



XXXIV. — Note on the Genus Pyrrhula. 

 By Edward Blyth, C.M.Z.S., &c. 



(Plate X.) 

 Until a comparatively recent period but one species of the 

 genus Pyrrhula, as it is now generally accepted, was recognized 

 by ornithologists. The Japanese race was not considered worthy 



