120 On the Use of the Term “ Homology.” 
19. Serial actinologues, 4. e. segments, parts, or regions of 
one part or organ which correspond with segments, parts, or 
regions of another serially homologous part or organ, e.g. a 
protopodite of an ambulatory leg and a protopodite of a swim- 
meret of the same lobster. 
20. Secondary actinologues, i.e. appendages annexed to 
successive segments, parts, or regions of a part or organ com- 
ared one with another, e.g. two appendages belonging re- 
spectively to two successive joints of an antenna, or two teeth 
of the same side of the same jaw. 
. Serial secondary actinologues, 7. e. appendages annexed 
to successive segments, parts, or regions of a part or organ 
compared with corresponding appendages annexed to succes- 
sive segments, parts, or regions of another and corresponding 
(serially homologous) part or organ, e. g. the radial tuberosity 
and the tibial trochanter, or processes of two successive bran- 
chial arches. 
25. General homologues, 4. e. parts of two organisms be- 
longing to the same general skeletal category, e.g. vertebral 
centra of man and the cod, or lateral appendages of the lobster 
and scorpion. 
In this way may be clearly distinguished different kinds and 
degrees of relationship perceived according as the mind is di- 
rected along one line of inquiry or another, whether concerning 
different individuals or different parts of the same individual 
and whether concerning derivation, process of development, 
relative position, or function. 
. These distinctions could, no doubt, be easily augmented or 
improved, and they are here set down for augmentation or 
emendation. 
_ it may or may not be well (I think it will be well) to dis- 
tinguish these different relationships by distinct terms; but 
* Special and general homologies were defined and explained by Profes- 
sor Owen in his book on the archetype and homologies of the vertebrate 
skeleton (pp. 1 & 72). e 
