72 COELENTERATA— PORIFERA phylum ii 



and is made up of fibres composed of three-rayed spicules, B. helvetica (Lor.). 

 Aptian ; La Presta, Switzerland. 



Appendix to Sponges. 



Incertae sedis. 

 Family. Receptaculitidae Roemer.i 



This singular group which ranges throughout the Ordovician, Silurian, 

 and Devonian systems, consists of globular, cup-, or platter - shaped bodies 

 containing a central cavity, and whose wall is composed of elements arranged 

 in quincunxial order. The substance of the wall is thought by Hinde to have 

 been siliceous ; calcareous according to Rauff ; aragonite according to Giimbel ; 

 calcite or chitinous according to Billings, either aragonite or chitinous in the 

 opinion of Girty. The elements lying on the outer or under side of the wall 

 have been usually described as consisting of small rhomboidal plates having 

 four transverse rays disposed crosswise, and one inwardly directed ray ; but 

 Girty has found evidence that the spicular summit plates are infiltrations of 

 the rhombic pits of the outer surface, and the radial pillars or spicules are 

 infiltrations filling radial tubes. 



The systematic position of these problematic fossils is wholly conjectural. 

 Giimbel assigns them to the calcareous algae (Dactijloporidae), and others to 

 the Foraminifera and Sponges. Hinde has referred them to the Hexadinellida, 

 but the observations of Rauff and Girty as to the original calcareous and 

 chitinous composition of the wall disprove this inference. 



Eeceptaculites Defrance. Spherical or pyriform bodies, with a central closed 

 cavity. Ordovician to Carboniferous. Europe, America and Australia. 



Ischadites Murchison {Didyocrinites Conrad ; Dkfi/ocrimis Hall). Conical or 

 ovate bodies, inclosing a central cavity, with a small summit aperture and 

 lacking an inner layer. Ordovician to Devonian ; Europe and America. 



Here are also referred Cijdocrinus Eichwald ; Pasceolus Billings ; Pohjgono- 

 sphaerifes Roemer; Cermiites Meek and Worthen; Lepidolites a,nd Anomalospongia 

 (Anomaloides) Ulrich. 



Range and Distribution of Fossil Sponges. 



The phylogeny of the Myxosfongiae, Ceratospongiae and a part of the Silici- 

 spongiae, owing to their' perishable organisation, remains involved in doubt. 



1 Salter, J. ir., Canadian Orgauic Remains, Dec. 1, 1859.— ^a?Z, /., Pal. N. Y., vol. i., 1847 ; 

 Geological Report of Wisconsin, 1862 ; Sixteentli Rept. N. Y. State Cabinet Nat. Hist., 1863 ; 

 Twelfth Rept. State Geologist of Indiana, 1883 ; Palaeontology of New York, vol. iii., 1859 ; 

 Eleventh Rept. State Geologist of Indiana, 1882 ; Second Ann. Rep. N. Y. State Geologist, 1883 ; 

 Palaeontology of New York, vol. vL, 1887. — Ulrich, E. O., Jour. Cincinnati Soc. Nat. Hist., vol. i., 

 1871; vol. ii., 1879. — Owen, J). J)., Geol. Report Iowa, Wisconsin and Illinois, 1844; Geol. 

 Survey of Wisconsin, Iowa and Minnesota, 1852.— Billinffs, E., Palaeozoic Fossils, vol. i., 1865 ; 

 Canadian Naturalist and Geologist, second ser., vol. ii., 1865 — Meek and Worthen, Geol. Survey of 

 Illinois, vol. iii., 1868. — Gilmhel, C. IT., Abhaudl. der k. bayr. Akad. Wisseusch., vol. xii., 1875. — 

 R.oemer, F., Lethaea Palaeozoica, 1880.— Hinde, G. J., Quart. Jour. Geol. Soc. London, vol. xl., 

 1884. — James, J. F., Jour. Cincinuati Soc. Nat. Hist., vol. viii., 1885 ; vol. xiv., 1891. — Walcott,C. D., 

 Mon. U. S. Geol. Surv., vol. viii., 188^.— Whitfidd, R. P., Geology of Wisconsin, vol. iv., 1884.— 

 Rauff, II., Zeit.schr. deut.sch. geol. Gesellsch., vol. .\i., 1888. — Nicholson and L>/dekker, Manual of 



Palaeontology, vol. ii., 1889 Wiuchell and Srlnteliert, Geol. of Minnesota, vol. iii., pt. 1, Pal. 



18^5— Ulrich, E. ()., ibid., ]\ 68.— Girl i/, G. I/., Fourteenth Ann. Rept. N. Y. State Geologist 

 for 1894, 1895. — Welli^r, S., Geol. Survey'of New Jersey, Rept. on Pal., vol. iii., 1903. 



