272 Mr. J. Crichton on a 



weaker. The bones of the rays of the gill-covers are longer 

 and much narrower. The tongue is longer, weaker, and 

 not so broad. The under jaw much weaker, and the dis- 

 tance between its rami one-third less. The teething much 

 more delicate. 



These are the principal distinctions which appear in the 

 external form and osteology of the head. In the latter 

 every bone differs, and the differences appear constant in 

 all that I have taken to pieces ; and in this state, therefore, 

 I have no hesitation in considering the parr perfectly dis- 

 tinct from any species or variety of trout we are acquainted 

 with, and entitled to hold a separate rank in our Fauna. 

 From the Migratory Salmon it is separated entirely by its 

 habits; and, I consider it should therefore stand in our 

 systems as the Salmo Salmulus of Willughby and Ray. The 

 correct distinguishing marks to be seen by a person who 

 has not leizure to make a minute examination, are the 

 great size of the pectoral fins, the shortness of the maxillary 

 bones, and consequent small gape, and the narrow breadth 

 between the rami of the lower jaw. 



Article IV. 



On a very powerful natural Magnet. By Mr. J. Crichton, 

 Glasgow. 



To the Editor of the Records of General Science. 



Sir, — The extremely small loadstone which belonged to 

 my deceased father, and of which you desire to receive 

 some details, is perhaps the most powerful of its kind ever 

 known. By the scientific reader it will probably be regarded 

 as a very curious and rare production of nature, while by 

 some others it may be thought to possess interest of a dif- 

 ferent description. Since no other person, now alive, knows 

 any thing of its history, I shall, from my own immediate 

 knowledge and circumstantial recollection, give the best 

 account of its origin, which at this time, it is possible to 

 put on record. 



In 1772, or the succeeding year, when Benjamin Franklin 

 was in Glasgow, he called on the late Professor Anderson. 

 Much of the conversation which took place between them 



