42 TITMOUSE. 



glitters like burnished gold. It often hangs, like a titmouse, 

 with its back downwards. * 



LETTER XVII. 



TO THOMAS PENNANT, ESQ. 



SELBORNE, June 18, 1768. 



DEAR SIR, On Wednesday last, arrived your agreeable 

 letter of June the 10th. It gives me great satisfaction to find 

 that you pursue these studies still with such vigour, and are in 

 such forwardness with regard to reptiles and fishes. 



The reptiles, few as they are, I am not acquainted with, so 

 well as I could wish, with regard to their natural history. 

 There is a degree of dubiousness and obscurity attending the 

 propagation of this class of animals something analogous to 

 that of the cryptogamia in the sexual system of plants ; and 

 the case is the same with regard to some of the fishes, as the 

 eel, &c.f 



* This elegant little species is the smallest of British birds ; its weight 

 seldom exceeds eighty grains. This minute bird braves the severest 

 winter of our climates. Two remarkable instances of its being migra- 

 tory are recorded by Selby- He says, on the 24th and 25th October, 

 1822, " after a very heavy gale and thick fog from the north-west, 

 thousands of these birds were seen to arrive upon the sea shore and sand- 

 banks of the Northumbrian coast." 



" A more extraordinary circumstance in the economy of this bird took 

 place during the same winter, viz. the total disappearance of the whole 

 tribe, natives as well as strangers, throughout Scotland and the north of 

 England. This happened towards the conclusion of the month of 

 January, 1823, and a few days previous to the long continued snow-storm, 

 so severely felt through the northern counties of England, and along the 

 eastern parts of Scotland. The range and point of this migration are 

 unascertained, but it must probably have been a distant one, from the 

 fact, that not a single pair returned to breed or pair the succeeding summer, 

 in the situations they had been known always to frequent ; nor was one 

 of the species to be seen till the following October." * ED. 



f Many absurd opinions have prevailed regarding the propagation of 

 eels, such as their originating from the hairs of the mane and tail of 

 horses thrown into rivers, with various other theories equally unfounded. 

 These have arisen from the circumstance that the roe of the eel does 

 not present the same appearance as that of other fishes. On this intricate 

 subject Mr Couch makes the following observations : " The generation 

 of eels has been involved in extraordinary obscurity, notwithstanding the 

 attention which eminent naturalists have paid to the subject. I have no 

 doubt that the pearly substance which lies along the course of the spine 



* Wernerian Memoirs, v. p. 397. 



