J. F. JAMES — THE GENUS SCOLITHUS. 



37 



ized to accept the positiveness of its evidence, because (1) of its anomalous char- 

 acter; (2) because it is found in a metamorphic rock, and may, therefore, have been 

 altered from some other species of organism, considerably different from the orig- 

 inal of the Scolithus. For instance, upon the supposition that the quartz rock is 

 middle Silurian, we should imagine the Fucoides rcrticalis of the < >neida conglom- 

 erate would change into a form not distinguishable from the Scolithus linearis." 

 This "quartz rock" is now regarded by Walcott as of lower Cambrian age. The 

 figure given by Hitchcock is not distinguishable from Scolithus verticalis, Hall (& 

 clintonensis of this paper). 



In the same year Mr. E. Billings* referred to S. linearis as occurring in the sand- 

 stone at l'Anse au Loup, strait of Belle Isle, differing from the common form of the 

 Potsdam of Canada, but being identical with that of the upper Primal of Pennsyl- 

 vania, and with that of the Potsdam of Tennessee (Number III of Safford). Bil- 

 lings then regarded the form as a plant. The rock at l'Anse au Loup is now 

 considered to be of lower Cambrian age. 



In the same volume f appears a description of a new species, under the name of 

 Scolithus canadensis. It consists of cylindrical or irregularly prismatic stems (or 

 rather the cavities in the rock once occupied by such stems) " from 1 to 2 lines in 

 diameter and from 1 to 6 inches in length, and either straight or more or less 

 curved. In some specimens several of the stems are in contact with each other, 

 and when this is the case and the stems have an angular shape they very much 

 resemble the coral Tetradium. The larger stems are more often straight than the 

 smaller. The true Scolithus linearis is generally larger and the stems straight and 

 parallel with each other. It occurs in the upper Potsdam of Canada and on the 

 eastern side of Snake mountain, Vermont." 



The species (figure 8) was illustrated in 1863 by Logan.J who described the holes 

 as being from fa to £ of an inch in diameter. They sometimes penetrate the rock 

 vertically several inches, but in gen- 

 eral they are more or less curved 

 and distorted. He says : 



"The casts of the interior of these cavities 

 in freshly hroken or unweathered masses 

 of the rock usually appear as solid cylindri- 

 cal or angular rods, composed apparently 

 of grains of sand cemented by a slightly 

 calcareous matter more or less tinged with 

 peroxide of in in. The origin of these holes 

 is not quite certain ; some suppose them to 

 he the remains of fucoids, others of corals, 

 while many are of the opinion that they 

 wire the habitations of small burrowing 

 marine or shore-frequenting animals." 



He also says that the original 



specimens upon which the species 



was founded differ from those above 



described "in being straight and 



inure decidedly cylindrical, and are therefore probably a distinct species." Tins 



remark is at variance witli the original description of Mr. Billings, as quoted above. 



l'*n. i re 8- Scolithus canadensis. {After Lesley. I 



* Paleozoic Fossils, l861-'66, p. _'. 



fl'. 96; tirst published in 1862. 



[Geology of Canada, from the commencement [of the Burvej | (" 1863. 



\Op. cit., \i. 943. 



Im.::. p. 101. 



