Manchester Memoirs, Vol. Ixi. (1917), A^c. 5. 7 



the genus, and the progressive numbers of the manuscript cata- 

 logue. As new, or other unenumerated, forms come to hand, 

 they are arranged a place in the serial list which belongs to 

 them, when their relationships are known; failing this informa- 

 tion they are put at the end of the section to which they appear 

 to belong, and often in alphabetical order, their indexed number 

 and name making them readily accessible. Every named form 

 is not necessarily written up in the linear series; but each can 

 be traced in the alphabetical list of the forms belonging to 

 the genus. At whatever point in the linear series at which they 

 are intercalated in the herbarium, they take the same numeral 

 as the form which precedes them, with a, b, c, or other dis- 

 tinguishing letter. 



The distinction between super- species, sub-species, race, 

 variety, form and the like, although recognised in the catalogue, 

 is not maintained in the index. All the names are thrown into 

 one alphabetical order, designed to find quickly their position 

 in the herbarium, and, as is explained further on, its representa- 

 tion in the herbarium of the different areas in which the species 

 occurs. 



The index includes the chief synonyms, but the indexing 

 proper is, in the main, confined to the names under which the 

 species is most generally circulated by collecting botanists. 

 Its purposes are to ensure easy reference tO' the place of any 

 plant in the boxes ; to record the geographical areas from which 

 the examples in the boxes have been derived ; and to show at a 

 glance what lacunae require filling up when any species is 

 offered. 



Besides the sequence of species, a sequence of the geo- 

 graphical areas has been observed throughout the entire her- 

 barium. As has been already indicated, Watson's divisions 

 have been followed for the British areas; and all Continental 

 species are arranged in the like sequence. In such large genera 

 as Rifbits and Rosa, where the number of boxes is considerable, 

 it would take up too much time to hunt for any species sought 

 unless the county areas were strictly followed ; in the British 

 section alone there are 1 1 1 boxes of R?fbi, and 65 of Roses, and 

 in the European section gi and 8g respectively. 



The same principle of maintaining a geographical sequence 

 for all the species included in the herbarium has been followed 

 in the Continental portion of the collection. Every species is 

 marshalled in one geographical sequence, which is maintained 

 throughout the herbarium. To effect this in the simplest man- 

 ner, Europe and the Mediterranean countries have been broken 

 up into sections according as their centres stand west or east 

 of the nth degree of west longitude, and north or south of the 

 50th degree of north latitude, Germany and Austria being 

 placed by themselves in a central group. Each area is repre- 

 sented by a numeral, or letter, to economise space when index- 

 ing the areas represented in the herbarium. 



