10 



bulletin: museum of comparative zoology. 



the most significant feature is the demonstration of the fact that the 

 strata at Martinsburg, containing the fauna with Strophomena trilo- 

 bata, gastropods, and Streptelasma, the so-called "Fusispira beds," 

 are younger than any of the limestone in the section at Trenton Falls. 

 This has a far-reaching effect, for the Fusispira beds extend across 

 Ontario and appear as the upper part of the Prosser limestone in 

 Minnesota, Wisconsin, and Iowa. 



description of new or interesting SPECIES.i 



COELENTERATA. 



Streptelasma corniculum Hall. 

 Streptoplasma corniculmn Hall, Pal. N. Y., 1847, 1, p. 69, pi. 25, fig. la-le. 



This species is one of the commonest in the lowest beds, but does 

 not appear again until horizon 390 is reached. Here, and again at 

 400, 410, and 440 feet above the base it is fairly abundant. Although 

 the specimens from the upper part of the Trenton are generally larger 

 than those from the basal beds, I cannot determine any specific 

 dift'erence between them. By making transverse and longitudinal 

 sections of large individuals I satisfied myself that these show 

 in their younger stages the characteristics of Hall's species (now 

 abandoned) <S. parvula. The specimens from the upper part of the 

 Trenton are well preserved, while those from the basal beds are for 

 the most part badly crushed. It was in these beds that I found this 

 species in such great abundance. One slab of rotten shale, about 

 one quarter of a square foot in area had on its surface no fewer than 

 forty specimens. 



Echinodermata. 



Cheirocrinus anatiformis (Hall). 



Plate 1, fig. 17. 



Echino-encrinites anatiformis Hall, Pal. N. Y. 1847, 1, p. 89, 318, pi. 29, fig. 

 4a^f. 



The discovery of a few specimens of this rare species is of interest, 

 since the exact horizon of the fossil has not previously been known. 

 Hall stated that his specimens were from the "midst of the fossili- 



1 Bull. 92, U. S. N. M. contains an extensive bibliography of the various species here 

 discussed. 



