34 
In conclusion he gives a list of names which he consid- 
ers satisfactory and permissible. 
Some of these stringent rules have been modified 
by later usage; others, again, have been ratified by the 
authoritative verdict of international conferences even 
down to as recently as the close of last century. That 
fact is testimony sufficient to the excellence of the sug- 
gestions which the youthful Swedish scientist, on his 
own initiative and without any forerunner to guide him, 
thus evolved and placed on record for the benefit of 
those who were to come after him. Some of ARTEDI'S 
above-mentioned rules of nomenclature bear consider- 
able resemblance to similar suggestions made by LIN- 
NAEUS in his "Fundamenta Botanica", to which circum- 
stance reference will be made below. 
After having dealt at length with Genera and ge- 
neric names, ARTEDI next turns his attention to lesser 
units, Species and Varieties. "In Ichthyology", he says, 
"every fish constitutes a Species which differs from 
other forms in the same genus in regard to some out- 
ward features, owing to something material being absent 
or present either as regards number, proportion or shape, 
or owing to some constant difference in colour". The 
points of distinction, however, between the various spe- 
cies may vary very considerably in kind and degree. 
The definition given is then illustrated by a series of 
examples which are critically discussed, occasion being 
thereby found to call attention to the need for caution 
as regards attaching weight to colour as a distinguish- 
ing mark, since the colour is apt to vary even in the 
same form. l One species-character that he recommends 
as reliable, is the number of spinal vertebrae in osseous 
fishes, but as care must be exercised in employing this 
test too, he proceeds to enjoin certain rules concerning 
it. As it not infrequently occurs that errors are made 
1 In connection with this point, ARTEDI complains about the 
difficulty of settling the compass "and scope of the various species 
belonging to the salmon-genus, a complaint which numerous ichthy- 
ologists since his day have undoubtedly felt ready to share. 
