LYMNEIDZ OF NORTH AMERICA. 169 
‘vidual (3) the posterior retractor was entirely separated from the 
anterior, the penis retractor being inserted at both ends; in another 
specimen (plate X, B) the penis retractor was entirely separated from 
the posterior penis-sac retractor, with many fine muscles connecting 
with the penis-sac. 
TABLE OF MEASUREMENTS. 
: Pros- Penis- 
Penis- Rec.sem. tate Vas. sac 
Penis. sac. duct. duct. def. retractor. Shell. Locality. 
1.00 2.25 3.00 1.50 3.00 1.00 19.50 Rochester, N. Y. 
1.00 2.00 3.00 2.00 4.00 1.00 18.50 <3 a 
1.00 2.25 3.00 1.50 4.00 1.00 19.00 ef S 
0.75 175 3.00 1.50 3.50 0.75 19.00 La Porte, Ind. 
The characteristic features of the genitalia of columella are the 
cylindrical form of the prostate, the larger size of the penis, the number 
of the penis-sac retractors and the insertion of the penis retractors 
on the posterior penis-sac retractor. 
RANGE: (Figure 12) Nova Scotia west to Minnesota, eastern 
Kansas and central Texas; Manitoba and Quebec (N. Lat. 52°) south 
to Texas and Florida (N. Lat. 27°). 
The records show that columella has a wide range throughout the 
eastern part of the United States. It does not occur in the great plains, 
its western extension seeming to be bounded by the edge of the prairie 
region of the Mississippi Valley (about longitude 100°). It is also 
absent (apparently) from the Appalachian Mountains. It is not a 
typical species of the great lakes, its center of distribution being at 
about the 40th parallel. Additional records are needed to establish 
its northern as well as its extreme southern range. Comparing the 
distribution with the regional map, we find that columella is found in 
the Canadian, Upper and Lower Mississippian, Nova Scotian, Caro- 
linian, and Rio Grandian regions. A single record from the Hudsonian 
region and one from Lake Superior (Dall) show that the species has 
a considerable range in this region. The records indicate that a rather 
wide area between northern Minnesota and Wisconsin, and Manitoba 
(Lake Winnipeg"), is badly in need of exploration. There is perhaps 
little reason for doubting the Manitoba records, but it would be very 
reassuring to have them confirmed by additional collections from this 
and adjacent territory. 
Columella occupies the drainage areas of two great river systems, 
the Mississippi and the St. Lawrence, as well as the various streams 
1No exact locality is given for this record and it is therefore not indi- 
cated on the distribution map. 
