134 LIVERPOOL BIOLOGICAL SOCIETY. 
This plan of making a compound specific name was 
first employed by Krohn in 1846,* and it was adopted 
by Traustedt in his admirable revision of the species of 
Salpe published in 1885,+ and I have decided to follow 
it in my forthcoming Report upon the ‘‘Challenger’”’ 
Tunicata, Part III. 
If this plan of using the compound specific name is not 
generally adopted, and if it becomes necessary to denote 
the species of Salpa by a single specific name, then the 
difficulty of choosing one of the names will have to be 
faced, and the following two alternatives would then 
present themselves: (1) to follow the law of priority only, 
without reference to the sexual condition of the form first 
named, and (2) to choose in all cases the earliest name 
applied to the sexually mature or chain form of the species. 
This second course, which in the case of Salpa seems the 
preferable one in some respects, would however result 
in a form being chosen to give its name to the species 
which is not larger, nor more highly organised, nor 
longer lived than the other form, but merely because it 
reproduces sexually. While if either of these two alter- 
native plans for choosing a single specific name were 
adopted, it would be lable to result in considerable 
confusion between the species as a whole and either of 
its constituent forms. For example, the name Salpa 
fusiformis is now generally used to indicate the aggregated 
form of its species, but it would if the second of the above 
plans were adopted come to be the name for both the 
solitary and the aggregated forms, and it might in some 
cases be difficult to tell in which sense the name was 
being used. 
The same difficulty will have to be faced in the case of 
* Ann, d. Sc. Nat. ser. 3, Zool., t. vi, p. 110. 
+ Bidrag til kundskab om Salperne, 
