38 



PROCEEDINGS OF WASHINGTON MEETING. 



In 1869 Billings read a paper before the Montreal Natural History Society on 

 Scolithus and allied fossils. This does not appear to have ever been published, but 

 from a notice of it given in Nature* we learn the author stated that sometimes the 

 specimens can be separated from the rock ; that all varieties are marked by undu- 

 lations; and finally, that specimens from the Potsdam of Canada found by the 

 geological survey "proved that they were not the casts of worm burrows, but 

 sponges." Siliceous spicules, generally elongate-pyriform, are found associated. 

 This is the only reference found in which the sponge nature of ScoIitJius is ad- 

 vanced. 



In 1877 Professor J. D. Dana, in giving an account of the researches of Reverend 

 Augustus Wing into the geology of Vermont, mentions a species of ScdMius under 

 the name of S. minutus.f It is not accompanied by any description, and I cannot 

 find that it has ever been described. The name was probably applied by W T ing to 

 some small worm burrows found during his researches. Professor Ezra Brainerd 

 has kindly sent me a specimen of this form, and it may be described as follows : 



Scolithus mintjtus, W r ing. Cavities penetrating the rock in various directions, 

 generally vertically and opening at right angles or obliquely to the surface. Holes 

 varying from ■£% to i of an inch in diameter; never branching, but sometimes 

 slightly curved (figures 9 and 10). 



It occurs in the Calciferous formation of Vermont, and its geological position is 



perhaps the only reason for considering 

 it distinct from S. canadensis. 

 In 1878 Messieurs Miller and Dyer de- 



Figure 9 — Scolithus mintitus. Wing. (Original.) 

 Surface, showing openings of burrows. 



Figure 10. — Scolithus minutus. Wing. (Original) 

 Showing burrows in rock. 



scribed a species of Scolith us under the 

 name of S. tuberosus.t It is quite differ- 

 ent from any other species of Scolithus 

 described. The authors say of it : 



" The holes (sometimes called stems) are curved or winding, and pass through the rock in an 

 irregular course, sometime uniting or branching, but never passing vertically through the strata 

 as in S. linearis, from the Potsdam group. Upon the upper surface of the rock the tubes are pro- 

 longed into a crateriform elevation, which is rarely at right angles to the surface of the rock. 

 These resemble, on a smaller plan, the mud elevations, thrown up around the holes, made by the 

 common crawfish on our fresh-water streams. 



"The holes are not. tapering, but maintain a somewhat uniform diameter. Diameter gencrally 

 about -1 lines; sometimes nearly 3. 



" This species resembles the burrow of some animal more clearly than any hitherto described, 

 and bears no resemblance to any of our fueoids. It has been frequently, but very erroneously, 

 referred to S. linearis." 



* Volume 1, 1800, pp. 248, 249. 



f Am. .lour. Sci., :!il sit., vol. xiii. Is77. p. :',42. 



J Privately printed pamphlet, entitled < lontributions to Paleontology, No. 2. 1878, p. 5. 



