ÖFVERSIGT AF K. VBTENSK.-AKAD. FÖRHANDLINGAR 1899, NIO 2. 43 



Pig. 1. Transverse section of some tubes, inagnified \-^. Fig. 2. Transverse sec- 

 tion, taken somewbat lower, |. Fig. 3. Longitudinal section, *-. 



A figure of an American, compact species, Tetr. fibratum 

 Safford from Harrodsburg, Kentucky, is also annexed, to show 

 the similarity of tbe apertures. 



In fact, every word with Avhich Safford bas described^) bis 

 Tetradium apertum can be applied to the specimen from Beeren 

 Eiland. 



I am thus in the position to confirm Safford's Statements 

 which have been somewhat besitatingly alluded to by låter 

 autbors. 



He says (1. c): »sometimes, bowever, tbey (the tubes) are 

 united in single intersecting series as in Halysites catenulatus 

 Linn.; not unfrequently too the tubes are isolated, or only uni- 



^) American Journal of Science 1856, vol. 22, p. 238. 



