Infinite graphs and bicircular matroids

B-matroids are a class of pre-independence spaces which retain many important properties of independence spaces. Higgs has shown that an infinite generalization of the cycle matroid of a finite graph which admits two-way infinite paths as circuits need not be a B-matroid. In this note it is shown that a similar generalization of the finite bicircular matroid is a ways a B-matroid. © 1977