SPONGES, GRAPTOLITES, CORALS. 



Cylinclrocoelia.1 



suggested by this fancied resemblance. The third is compressed vertically and 

 shows the radial arrangement and bifurcation of the compressed lobes very satis- 

 factorily. As near as can be determined, the original dimensions of a specimen of 

 medium size were about as follows: hight, 90mm.; greatest width, 80 mm.; dia- 

 meter of stem 15 mm.; thickness of lobe, 8 mm.; thickness of walls of sponge, 0.5 

 mm., or less. 



"The spicules of the inner layer, owing to alteration and replacement by 

 calcite, have not been determined. A thin section, however, shows that it was 

 minutely porous, the tissue separating the pores thin, and the pores of variable 

 size, the larger ones of rounded form, the smaller ones more or less angular. The 

 surface, as in B. filosa, is striated, only the striae are much finer and more irregular. 

 The appearance of the surface is to be described as hirsute rather than filose." 



Formation and locality. From the Trenton shales at Minneapolis and St. Paul, Minnesota. 

 Collector. Mr. E. O. Ulrich. 

 Mus. Beg. No. 8225. 



Order CALCI8PONGLE,* Blainville. 

 Family PHAEETRONES, Zittel. 



CYLINDROCCELIA, Ulrich. 



1889. Cylindroccelia, ULRICH. American Geologist, vol. iii, p. 245. 



1891. Cylindroccelia, JAMES. Jour. Cincinnati Soc. Nat. Hist., vol. xiv, p. 56. 



Original description. " Sponges free, cylindrical, or nearly so. with the lower end 

 tapering rapidly to a point, or truncate. A central cloaca extends throughout at 

 least the subcylindrical portion. It is of tubular or very elongate conical form, 

 widening gradually upwards. Walls thick, traversed by irregularly disposed radi- 

 ating canals. Very few of these penetrate the thin and compact dermal layer which 

 covers both the inner and outer surfaces. When the- dermal layer is worn away 

 their sub-circular mouths appear. Skeleton, apparently very finely porous. The 

 specimens are too much altered to admit of determining its elemental component. 



"Type, C. endoceroidea Ulrich. 



" Sponges of this genus are liable to confusion with slightly tapering forms of 

 Orthoceras and Endocerns. The absence of septa and presence of canals should, of 

 course, distinguish them at once." 



*The systematic position of these sponges is that of Mr. Ulrich. Geol. Survey of Illinois, vol. viii, p. 239. 1890. 



