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ROCHESTER ACADEMY OF SCIENCE. 



the filling of a system of branched passages, later, that it represents a 

 spiral cavity, which he is inclined to think served as a repository for 

 eggs rather than as a dwelling. In this connection he points out a 

 resemblance between the form of Taonicrus and that of the spirally 

 enrolled spawn bands of certain gastropods. More recently he has 

 attempted to show by experiments in blowing through a slender tube 



upon fluid clay, that structures 

 analogous to Taonuriis might be 

 produced by various physiological 

 movements. 



The explanation of the nature 

 of Taonurus, presented here in 

 brief, was suggested in a recent 

 study of Dadalus (Rouault)* by 

 the general resemblance of Tao- 

 miriis to that form. The material 

 upon which this explanation is 

 based is from the Esopus and 

 Hamilton formations of the middle 

 Devonian in New York. In col- 

 lecting it special pains were 

 taken to note the position of the 

 fossil in the beds. 



Taomims may be described 

 as thin plates occurring nearly 

 horizontally in the rock, from 

 which they are frequently sepa- 

 rable. These may be roughly 

 U-shaped or suboval in outline 

 (see Figure i) or irregularly 

 lobate, or may form inverted 

 archimedean spirals, either dex- 

 tral or sinistral, in which the successive volutions increase in size 

 downward (see Figure 2). An individual volution has the appear- 

 ance of a flat cone with the apex directed upward. Many of the 

 spirals are more or less lobed in outline. Both faces of these plates 

 are marked by a series of curving lines or ridges. In the U-shaped 



-U-shaped form of Taoiiuriis; 

 c, cylinder. 



* " Arthrophyctis and Da-dalus of Burrow Origin ",• Proc. Rochester Acad, of Sci. vol. 4; 

 1906, pp. 203-210. 



