RANGE OF HELICID^: EPIPHALLOGONA, ETC. 
395 
Though this group is uow a waning oue in the Old World, it is the 
most advanced and dominant one on American soil, having crossed 
by the Aleutian bridge and invaded North America, but being pre- 
vented by the intervening arid and mountain regions from effective 
eastward extension, spreads southwards along the Pacific shores, 
eventually penetrating to South America and the West Indian Islands, 
probably reaching the latter area by way of Yucatan, as the Euadenia 
have not yet invaded the Lesser Antilles. 
The Epiphallogona (errl, upon ; (fxiXXos, penis ; yoros, seed), of 
which Pilsbry’s West Indian Teleophallogona seems an earlier form, 
the more characteristic species of which retain an additional flagellate 
appendix to the male organ, is remarkable for the development of 
an epiphallus and flagellum upon the penis and by the total lack of 
the dart apparatus. 
This somewhat primitive group has probably 
originated in the same area and travelled by the 
path that the much later developed Euadeniate 
forms afterwards followed, and have been driven 
still further from the evolutionary centre by the 
Euadeniate migrants, whose advance guard over- 
laps the districts they occupy. Though still found 
in South Eastern Asia, from Japan to India, they 
now chiefly occupy the ef|uatorial and tropical 
islands of the Indo-Malayan region and the adja- 
cent Australian continent, 'fliey preceded the of ^ thf "ErTphXgona! 
Euadeniate race in America, by whom they have eCnsoMafer sf^ 
been driven towards the south, occupying at the 
present time Central America, the whole of the West Indian Islands 
and Northern South America, often associated with the competitive 
Euadenia, but extending beyond them on all sides, except along the 
route by which the newer and stronger race are advancing. 
The Proto gona (TrpwTos, first ; yoi-os', seed), as the still simpler 
forms are denominated, possess the simplest genitalia, without any 
accessory organs, as dart sac or mucus glands on the vagina and 
without epiphallus or flagellum on the penis. 
This group, which formerly overspread almost the entire globe, is 
of still more ancient origin, and having been driven entirely from 
tbe northern hemisphere in the old world by the series of more 
advanced forms which successively followed them they now exist 
