554 PROCEEDINGS OF THE ACADEMY OF [1895. 



in his T. dubium, but it is very different from the type of that species 



in its pod. 



The third species, Dr. Davidson's T. dubium, as to the typical 

 plant, is an excellent one by the sharply rhombic cross-section of the 

 short pod. In the only specimen of his which I have access to, there 

 is no instance of that twist in the pod which he assigns to the species ; 

 whence I infer that he has included in it, the preceding ; but the 

 essential character of that is its extremely long and narrow very flat 



pod. 



The fourth species, T. rapparideum, is such a remarkable con- 

 necting link between two or three distinct natural orders, that 

 herbarium botanists of the old school would naturally sit more at 

 ease if such a plant had not been discovered. It has invariably a 

 4-valved pod and 4 placentae. The valves separate from the 

 placenta? beginning at the top, just as in the capparids ; and when all 

 four of the valves have fallen away, the four placenta?, joined 

 together at the summit, remain in place, quite as in certain genera 

 of Papaveracea*. The pods are constantly devoid of every trace of a 

 partition, and there is not the least suggestion of anything anomalous 

 about the plant, In its locality it is even more abundant than any 

 other species, and less disposed to vary than is the typical species of 

 the genus. The statement in the Synoptical Flora, p. 141, as to the 

 capsules, " commonly containing a small capsule-like structure at 

 base," it is based on a single instance. Dr. Robinson's imagination 

 would seem to have led him to guess that this malformation may be 

 common. I alone have seen more of this plant than have all other 

 botanists, by at least tenfold, and am prepared to say that no species 

 of the genus is less variable in its fruit, or more constant in all its 

 excellent specific characters. 



