Taxonomic Anomalies 669 



at the base united. The lemon-scented Euca- 

 lyptus citriodora is one of the most widely 

 known cases. In other instances the peltate 

 leaves become more or less hollow, constituting 

 broad ascidia as in the case of the crassulaceous 

 genus Umbilicus. 



This connation of the basal lobes is universal- 

 ly considered as a good and normal specific 

 character. Nevertheless it has its manifest 

 analogy in the realm of the anomalies. This is 

 the pitcher or ascidium. On some trees it is of 

 quite common occurrence, as on the lime-tree 

 {Tilia parvifolia) and the magnolia {Magnolia 

 obovata and its hybrids). It is probable that 

 both these forms have varieties with, and others 

 without, ascidia. Of the lime-tree, instances are 

 known of single trees which produce hundreds 

 of such anomalous leaves yearly, and one such a 

 tree is growing in the neighborhood of Amster- 

 dam at Lage Vuursche. I have alluded to these 

 cases more than once, but on this occasion a 

 closer inspection of the structure of the ascidium 

 is required. For this purpose we may take the 

 lime-tree as an example. Take the shape of the 

 normal leaves in the first place. These are cor- 

 date at their base and mainly inequilateral, but 

 the general shape varies to a considerable ex- 

 tent. This variation is closely related to the 

 position of the leaves on the twigs, and shows 



