PROTOZOA. 291 



ISCHADITES, MuRCHisoN. 1839. 



ISCHADITES SQUAMIFER. 



PLATE XXIV, PIGS. 1, 2. 



Dictyocrinites, Conrad. Ann. Rept. Geol. Survey, N. Y. 1841. 



DUtyocrinus gquamifer, Hall. Pal. N. Y. Vol. iii, p. 135, p. 7a, figs. 11-13. 1859. 



Beceptaculites " " Rejiort of State Geologist for 1882. Expl. pi. 23, figs. 1, 2. 1883. 



Body pyriform, regularly rounded on the base, conical above and perforate at 

 the summit by an aperture about 5 mm. in diameter. The summit plates of 

 the spicules have curved edges and appear to imbricate, the lower sides being 

 depressed below the anterior edges of the adjacent inferior plates. In the 

 zonal region the plates have a width of from 1 to 2 mm., and their size 

 decreases very gradually towards the base and quite rapidly towards the 

 summit, where they have a width of less than 1 mm. The vertical spicular 

 rays were very slender, having a thickness of about 5 mm. from their distal 

 extremities. The original specimen figured by Mr. Conrad has a height of 

 34 mm., and a diameter of 33 mm. at the lower third of the height. 



Specimens of this species are quite uncommon and so far as observed they 

 are usually completely filled with chalcedony. The type specimen, however, 

 is filled with calc spar. 



Formatum and locality. In the limestones of the Lower Helderberg group at 

 Schoharie, N. Y. 



ISCHADITES BCRSIFORMIS. 



I'l.ATK XXIV, FIGS. I'J-U. 

 ReceptacfUiUs bandformis, Halu Report of State Geologist for 1882. Expl. pi. 23, figs. 12-14. 1883. 



The original form of this sponge is not clearly shown in the specimens at hand 

 on account of the various degrees and directions of compression to which 

 they have been subjected. Three specimens are sub-pyriform with terminal 

 summits, and two are discoidal with eccentric summits. The zonal plates 

 have a width of about 2.5 mm. Near the summit they are small and very 

 numerous, and have a width of about 1 mm. None of the specimens show 



