ANCIENT LAND CONNECTIONS 
411 
the members of this genus is their astonishing resemblance, 
as mentioned before, to certain species of the European group 
Helicigona, including the well-known Arianta arbustorum. 
Some of the American shells are externally so much like the 
latter that they were placed into the same genus until recently. 
Dr. Pilsbry,* however, maintains that the European Heli¬ 
cigona differ anatomically from Epiphragmophora, and that 
the two should be placed in quite distinct groups. Even on 
anatomical grounds opinions may differ very radically, for 
Dr. von Ihering claims that the American Epiphragmophora 
and the members of the group Helicigona are genetically con¬ 
nected. After careful examinations of the European Arianta 
arbustorum and the Argentine Epiphragmophora tucuma- 
nensis he could perceive no noteworthy anatomical difference 
between the two, and placed them both into the same genus. 
If Dr. von Ihering’s f observations are correct, this is another 
example of the same extraordinary relationship between Euro¬ 
pean and west American forms that I have had occasion to 
point out in previous chapters. Occasionally this relation¬ 
ship manifests itself only in Europe and south-western North 
America. In other cases it exists simply between European 
and western South American forms. In this case both the 
American western centres are related to the European centre 
of dispersal. It clearly illustrates, as stated before, that 
Europe was once joined to a mid-Atlantic land bridge which 
communicated directly with a belt of land lying to the west of 
America. On the disappearance of the latter many of the 
animals inhabiting that belt of land took ref uge in the western 
parts of America and still persist there. 
Epiphragmophora, all the same, does not clearly reveal the 
special affinity that exists among the older forms of animal 
life of south-western North America and southern South 
America. The wingless insects known as “ bristle tails ”(Thy- 
sanura) are generally looked upon as a very ancient group. 
Among these the genus Japyx, which is easily recognisable 
by its forceps-like tail-appendage, has a noteworthy distribu¬ 
tion. Japyx solifugus occurs in the Mediterranean region, 
* Pilsbry, II. A., “Manual of Conchology (Pulmonata),” IX., p. 195. 
t Ihering, II. von, “ System der Heliciden,” p.422. 
