693 



C — is forty-five inches in length, and has forty joints ; these, from 

 the first to the fifteenth inchisive, are branchless, the sixteenth has one 

 branch, the seventeenth has two branches, the eighteenth has thirteen, 

 the nineteenth eleven, the twentieth nine, the twenty-first nine, the 

 twenty-second ten, the twenty-third ten, the twenty-fourth seven, the 

 twenty-fifth eight, the twenty-sixth two, the twenty-seventh two, the 

 twenty-eighth two, the twenty-ninth one, the thirtieth three, the thir- 

 ty-first none, the thirty-second two, the thirty-third none, the thirty- 

 fourth one, the thirty-fifth and thirty-sixth none, the thirty-seventh 

 two, the thirty-eighth two, and the thirty-ninth and fortieth none. 



D — is forty inches in length, and has thirty joints : from the first to 

 the sixteenth inclusive, and also the eighteenth, twenty-fourth, twenty- 

 seventh, twenty-ninth, thirty-first, thirty-third, thirty-fifth, thirty-sixth 

 and thirty-eighth are branchless ; the seventeenth, nineteenth, twenty- 

 first, twenty-third, twenty-fifth, twenty-sixth, twenty-eighth, thirtieth, 

 thirty-second, thirty-fourth and thirty-seventh, have one branch each, 

 the twentieth has two branches, and the twenty-second three branches. 



It should also be observed that stems, which at first are perfectly 

 unbranched, often throw out a few scattered branches as the season 

 advances, so that it is almost impossible to lay down any formula of 

 branching that shall be at all constant. 



In barren stems the apical joints appear to be invariably branchless 

 and very much attenuated, while the median and lower joints are ge- 

 nerally more or less branched : the inferior branches, especially when 

 their insertion is submerged, are much stouter than the superior ones, 

 and are often furnished with whorls of branches, like the main stems. 



THE WOOD EQUISETUM. 



Equisetdm sylvaticum, Linneus. 



This plant, although local, is very widely distributed, occurring in 

 moist shady woods throughout the kingdom. In the vicinity of Lon- 

 don it grows in several woods in the Hampstead and Highgate dis- 

 trict : at the latter place it was observed as long since as the time of 

 Lobel, who records the habitat in his ' Illustrationes Stirpium,' * pub- 

 lished in 1655, disguising the English appellation of * Highgate,' un- 

 der the scientific term of 'Alice Portce.^ The other English habitats 

 with which I have been furnished through the kindness of correspon- 

 dents are so numerous that a mere list of them would exceed the space 



* lUus. Stirp. 141). 



