436 III. SEGREGATES AND 
by other Floras,—say, by those of Hooker or Bentham,—how 
are we to understand their names as. applicable to the eight 
segregates of the ‘Manual’? All becomes inconsistency and 
confusion ! 
But without going outside the one book, the ‘Manual’ in its 
successive editions, the diversity of names, and especially the 
diversities in their meanings, is sadly perplexing. Here are the 
dates and names; the alleged species being numbered as a dis- 
tinction between them and their included or component varieties : 
1843. 1851. 1856—67. 
1. aquatilis. 1. aquatilis. 1. trichophyllus. 
a. heterophyllus. a. heterophyllus. 2. Drouetii. 
b. pantothrix. b. trichophyllus. 3. heterophyllus. 
c. subpeltatus. 4. confusus. 
2. confusus. 5. Baudotii 
1847. 6. floribundus. 
1. aquatilis. 7. peltatus. 
- heterophyllus. 8. pseudo-fluitans, 
- peltatus. added in 1867. 
Thus, in tracing backwards, the eight species of 1867 were 
compressed into two species, one of them composed of three 
varieties, before 1856 ;—into one species, of two varieties, before 
1851;—into one species, of two other varieties, before 1847 ; 
that is, the two varieties of 1847-1850 not corresponding with 
the two preceding varieties of 1843—1816. 
If it be wished to trace the distribution of any one of the seven 
or eight nominal species of 1856—1867, either by help of records 
made before 1856 or by records made since that date by botanists 
to whom the newly dissevered species are unfamiliar,—how is it 
to be done? The name aquatilis used before 1856, or since that 
date under the conditions mentioned, may mean any one of them, 
except perhaps confusus in the latter part of the time. Again, 
the name heterophyllus uscd as the only alternative of pantothrix 
in 1818, must have had quite a different meaning from that of the 
same name used as the only alternative of peltatus in 1847. So, 
the heterophyllus of 185], as the third alternative ayainst both 
