OTTAWA VALLEY CONCRETIONS 633 



Saxicava arctica, for example, drives straight burrows deeply into the 

 sand and they may still be found abundantly in them near the structures 

 described. The filling of these burrows by the still semi-fluid blue sea- 

 ooze under sand pressure might result or they might have been filled by 

 the animals constructing them. 



The burrowing habits ascribed to Balanoglossus, a soft, worm-like 

 marine animal belonging to the phyllum Chordata which is common along 

 parts of the Atlantic coast, might suggest that a representative of this 

 genus or some other creature of similar habits produced the clay-filled 

 burrows of the Pleistocene sands at Eideau Junction. The following 

 notes on the burrows of Balanoglossus by Alice R. ^orthrop*^ refer to a 

 species found in the Bahama Islands : 



"Followed one of the holes down straight about 10 inches, then along in a 

 spiral for about 18 inches to the rock, where I found a Balanoglossus. Fol- 

 lowed two more holes, but lost them before reaching the animal. When found, 

 the whole animal is surrounded by a transparent gelatinous coating. Laid 

 one on paper ; when extended, it is 12 inches in length. Some were over 2 

 feet long." 



The noteworthy features of this description of Balanoglossus and its 

 burrow, with reference to fossil burrows, are the combination of direct 

 and spiral courses shown in the same burrow. The contrasted types of 

 spiral and straight burrows are characteristic of some of the clay tubes 

 at Eideau Junction. The power of strong contraction possessed by a 

 worm-like body 1 or 2 feet in length, if exercised within a burrow in soft 

 sand, would be very likely to give rise to great irregularities in the size 

 and shape of the burrow. Deposits of slime and mucus like those ascribed 

 to Balanoglossus would doubtless still further accentuate such irregu- 

 larities. Some marine creature producing burrows comparable with that 

 of Balanoglossus seems more likely than the straight boring Saxicava to 

 have formed the curious irregular-shaped clay-filled burrows at the 

 Eideau Junction sand pits. These structures belong in the class of fossil 

 burrows or pseudoconcretions. 



Summary 



The concretions described in this paper belong to well defined types 

 characterized by physical features which can be readily discriminated. 

 The areal distribution and geological range of these types are determined 

 (1) by the presence or absence of the lithologic features essential to their 



J. I. Northrop : A Naturalist in the Bahamas, p. 5. Columbia Univ. Press, 1910. 



