On Plants collected in the line of the Rideau Canal. 1 1 



ject of the Diatomacea, I have succeeded in detecting the mature 

 sporangia of the Gomphonema therein mentioned, as well as those 

 of Gomphonema minutissimum, Ag., and Cocconema lanceolatum, 

 Ehrh. In these three species each conjugated pair of frustules 

 gives origin to two subcylindrical, somewhat fusiform, trans- 

 versely striated sporangia, which lie in a direction parallel to the 

 empty frustules instead of across them, as in Eunotia turgida. 



Around each conjugated pair of frustules is at first developed 

 a considerable quantity of firm mucus or gelatine, which however 

 gradually disappears as the sporangia become mature. The pre- 

 sence of this mucus affords the readiest means of detecting the 

 conjugated state of Gomphonema and Cocconema, which is likely 

 to escape observation owing to the great resemblance of their 

 sporangia to frustules, especially to those of Cocconema : this re- 

 semblance is so striking in Cocconema lanceolatam, that the prin- 

 cipal apparent difference between the sporangia and the frustules 

 of this species consists in the far larger size of the former. 



III. — Notice of Plants collected in the line of the Rideau Canal, 

 Canada West. By Philip Whiteside Maclagan, M.D., 

 Royal Canadian Rifle Regiment *. 



The plants were collected in May 1843 on the line of the Rideau 

 Canal. This great work, which commences at By town on the 

 Ottawa and terminates near Kingston on Lake Ontario, was con- 

 structed several years ago by the Royal Engineers in order to 

 obviate the disadvantages of the frontier route from Upper to 

 Lower Canada. Its length is 137 miles, but like our own Cale- 

 donian Canal its course is naturally marked out by a string of 

 lakes and rivers, so that the extent of actual canal is very small, 

 but there is a very extensive series of large locks and dams for 

 rendering the shallow streams connecting the lakes navigable. 

 The summit level of the canal is 290 feet above By town, so that 

 there is not sufficient elevation to affect the character of the ve- 

 getation ; but in other respects there is sufficient variety in soil 

 and situation to produce a good deal of diversity in the botany of 

 the different stations on the line. As I happened to be passenger 

 in a very slow steamer which occupied nearly four days in the 

 transit, I had an opportunity of examining a good deal of the 

 country, and on several occasions, by walking on from one lock 

 to the next, collected a good many plants before the vessel came 

 up. The points which I examined most minutely were — Smith's 

 Falls, about half-way between Bytown and Kingston ; the Isth- 

 mus and Davies's Locks some miles further on ; Jones's Falls, 



• Read before the Botanical Society of Edinburgh, May 13, 1847. 



