Ul\" RSITY OF ILLlKjiS LIBRARY AT URBANA-CHAMPAIGN NATURAL HIST. SURVEY FIELDIANA • GEOLOGY Published by CHICAGO NATURAL HISTORY MUSEUM Volume 10 October 5, 1950 No. 10 A MIDDLE DEVONIAN OCTACTINELLID SPONGE FROM NEW YORK Eugene S. Richardson, Jr. Curator of Fossil Invertebrates The specimen of fossil sponge described in these pages was collected in situ from an exposure of the Middle Devonian Onondaga limestone in an abandoned quarry off New York Route 5 (Buffalo to Batavia road), near Snyder, New York. This quarry is the site of the largest fossil coral reef in western New York, and has yielded many important fossil specimens, particularly corals and bryozoans. It is also the place where fragments of the large spiny trilobite, Terataspis grandis (Hall), were discovered. Fossil sponges of the octactinellid genus Astraeospongia are found in the Silurian and Devonian beds of Europe and North America. Most species are known only from their dissociated star- shaped spicules. These spicules are characterized by a central disk from which radiate six rays, of equal length in most species, spaced at 60° from each other, in the "horizontal" plane. Perpendicular to this plane, two "vertical" rays spring from the central disk, one above and one below. Species known only from spicules are differentiated on (a) the diameter of the spicule through opposite horizontal rays; (6) the character of the vertical rays, which may be as long as the horizontal rays, shorter, or not developed at all; (c) the shape of the individual ray; and (d) characters of the central disk and axial canals. The spicules seem to have been placed in the living sponge in no regular orientation, except that the horizontal rays were usually parallel to the plane of the surface. Hinde (1888) has noted the presence of the axial canal, which, however, is usually obscured by an alteration of the originally siliceous spicules to calcite. Hall and Fritz-Gaertner (1878) have reported an amazingly intricate structure of that canal, coupled with a curious interpretation of the mode of growth of the spicule. D'Arcy Thompson (1942), while satisfactorily explaining the development No. 650 79 80 FIELDIANA: GEOLOGY, VOLUME 10 of the tetractinellid and hexactinellid forms, does not discuss the octactinellid shape. Indeed, it is difficult to understand this geo- metrically simple form in terms of the physico-chemical processes giving rise to the others. Five species have been described from European occurrences of this genus, one ranging from Late Ordovician to Middle Silurian, and four in the Middle Devonian. Eight species have been described from North America, one, the genotype, Astraeospongia meniscus (Roemer 1848), from the Middle Silurian1 and seven from the Middle Devonian, as that division is generally understood. The distinction between some of the North American Devonian species, however, may be more apparent than real, as six of them are known only from scattered spicules. The criterion of spicule diameter, on which many descriptions depend, can be significant only in combina- tion with other definitely distinctive features, for there is great variation in size of spicule within a single sponge. Roemer (1861, p. 14) noted a "mingling of thick and coarse-rayed stars with solitary dainty fine-rayed stars" in both A. meniscus and A. patina. Lowen- stam (1948, p. 86) interprets these as respectively dermal and somatic spicules. NOMENCLATURE OF THE GENUS ASTRAEOSPONGIA ROEMER 1854 The name of the genus has been cited as Astraeospongia almost exclusively since Roemer (1860, p. 14) used that spelling. In his original description of the genus (1854, pp. 155-156), he proposed the name as Astraeospongium, though referring in the same text to Spongia and Acanthospongia, with the Latin feminine ending. The name Astraeospongium (neuter) was derived from the Greek airoyyiov (neuter), meaning "a fragment of sponge." Roemer incorrectly translated this word to the Latin spongia, while correctly transcribing it "spongium." Other names of sponge genera from the same ultimate root stem through the Latin from the Greek o-Toyyia (feminine); Roemer's emendation was probably made to be consist- ent with this usage. There was no justification, under the Rules of the International Commission on Zoological Nomenclature, for Roemer's subsequent change in the spelling (see Moore, Weller, and Knight, 1942). Nevertheless, the change has been made, and has been consistently 1 There is also "Astraeospongia, n. sp." of Lowenstam (1948, p. 106), from the Middle Silurian of Indiana and Illinois, regarded by him as ancestral to A. meniscus. Lowenstam has also reported an isolated spicule from the Early Silurian of Illinois (loc. cit.). RICHARDSON: A NEW MIDDLE DEVONIAN SPONGE 81 followed for ninety years. Therefore it appears that stability is best to be served by preservation of this originally unwarranted emendation. A communication regarding this matter has been Fig. 33. Astraeospongia clauda, sp. nov. Oral surface as exposed by weathering on a bedding surface of Onondaga limestone. Spicules are dark; matrix is light. Holotype, C.N.H.M. PE999. XV2. placed before the Secretary of the International Commission on Zoological Nomenclature. Phylum Porifera Class Silicispongiae Subclass Octactinellida Order, Family, etc., not named Astraeospongia Roemer 1854, emend. Roemer 1860 Astraeospongia clauda, sp. nov. Holotype. — C.N.H.M. PE999, a complete but crushed specimen. 82 FIELDIANA: GEOLOGY, VOLUME 10 Horizon and locality.— Middle Devonian, Onondaga limestone. Collected by Dr. Sharat K. Roy and Mr. Max Kopf, August, 1949, Williamsville Quarry, near Snyder, New York. Diagnosis. — A large Astraeospongia, probably of cup-like shape, about 10 cm. in diameter. Spicules from 2 to 73^ mm. in diameter, with horizontal rays straight, bent, or curved, of various thicknesses, some slightly constricted proximally. Many spicules with one hori- zontal ray conspicuously longer than the others. Vertical rays not Fig. 34. Astraeospongia clauda, sp. nov. Cross section on a diameter, oral surface at top. The shape is the result of collapse of an originally cup-like form. Holotype, C.N.H.M. PE999. XI. developed. Diameter of central disk about equal to thickness of spicules; this disk may or may not be set off by a proximal constric- tion of the rays. Horizontal rays parallel to sponge surface. Spicular axial canals present, probably simple, cylindrical or tapering. Canal system of sponge unknown. Discussion. — The present disk-like shape of the flattened fossil (see fig. 33) is similar to that of some Silurian specimens of Astraeo- spongia meniscus (cf. Lowenstam, 1948, pi. 3). Lowenstam (ibid., pp. 85-86, 88-104) presents an exhaustive analysis of the conditions of fossilization and preservation resulting in this shape. Though the present specimen reveals only meager evidence of its history, it probably represents a bowl-shaped sponge, flattened in the same way as the Silurian fossils. The original sponge, then, must have been shaped much like A. meniscus. Like some of the specimens of the latter species observed by Lowenstam, the fossil in hand has a central depression on the oral surface, simulating an osculum, probably induced by the crushing (see fig. 34). The dermal spicules (see figs. 35 and 36) are significantly different in shape from any others described in the genus. However, it seems inappropriate to erect a new genus for their reception. The vertical rays are undeveloped, a common condition in the group. All spicules have the normal number of horizontal rays, but they are Fig. 35. Astraeospongia clauda, sp. nov. 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Mm ■5' . c s c 2 1 . 03 I d c • 03 II ■ o> M9 U3 bS ■t •2oi Oi W >-H 3*1 e _ "3 c u 3 u rt is ?s . 03 • o> ^tf ^tf "S 5 •^CQ 85 86 FIELDIANA: GEOLOGY, VOLUME 10 neither equally spaced, of equal length, of equal diameter, nor straight. A random selection of spicules is shown in figure 37, from camera lucida sketches. The rays curve or bend unsystematically. Though many spicules have undoubtedly been disarranged in the Fig. 37. Spicules of Astraeospongia clauda, sp. nov. Rays terminating in a jagged line pass beneath the matrix or another spicule. The black line represents one millimeter, to the same scale of magnification as the spicules. Camera lucida drawings from holotype, C.N.H.M. PE999. X5. sagging of the sponge, several groups on the oral surface have ap- parently remained in their original mutual relations. In these groups, some of the bent rays interlock, indicating that their bending is probably the result of mutual interference and adjustment during growth. Where a ray meets a neighboring spicule, it either stops or continues across the other. In the fossil state, the crossing rays are deeply imbedded into those crossed. As this seems an im- possible situation if the mineral spicule is formed either on the sur- face of a cell, as D'Arcy Thompson shows for certain forms, or within a polynucleate syncytium, as shown by, for example, Hyman (1940, pp. 300, 301), the imbedding of these rays may have occurred during the alteration of the siliceous spicule to calcite. Both bent and mutually impressed rays can be seen rarely in calcified spicules of undeformed specimens of A. meniscus from Decatur County, Tennessee (specimens in Chicago Museum collection). RICHARDSON: A NEW MIDDLE DEVONIAN SPONGE 87 The rays of certain spicules narrow abruptly, the distal portion having a much smaller diameter than the proximal. It seems likely that this thin extension represents a filling of the axial canal; its diameter is about one-fifth the diameter of the ray. The spicules, probably originally of silica, are now composed of crystalline calcite. The interior of the sponge body, exposed by a saw cut on a diameter (see fig. 34), is composed of crystalline calcite, probably representing a mass of altered spicules. Shapes of spicules within the body are not determinable; if there are somatic spicules with vertical rays, they are not to be seen. Comparisons.— The irregularity of form of the spicules sets this species off from all other species of Astraeospongia, yet occasional deformed spicules in specimens of the genotype itself show that the relationship is not distant. In diameter, the spicules are most closely comparable to the more slender and regular spicules of A. meniscus. The table compares the characters of the spicules of the several species. REFERENCES Hall, J. W., and Fritz-Gaertner, R. 1878. On the structure of Astraeospongia meniscus. 30th Ann. Rept. N. Y. State Mus. Nat. Hist., pp. 111-116. Head, W. R. 1895. Palaeozoic sponges of North America. Chicago. Hinde, G. J. 1888. A monograph of British fossil sponges, 1. Palaeontographical Society, volume for 1887. London. Hyman, L. H. 1940. The invertebrates: Protozoa through Ctenophora. New York. Lowenstam, H. A. 1948. Biostratigraphic studies of the Niagaran inter-reef formations in north- eastern Illinois. 111. State Mus. Sci. Pap., 4. Meek, F. B., and Worthen, A. H. 1868. Palaeontology. Geol. Surv. 111., 3. Moore, R. C, Weller, J. M., and Knight, J. B. 1942. Erroneous emendation of generic names. Jour. Paleont., 16, pp. 250-261. Reimann, I. G. 1945. New Middle Devonian octactinellids. Bull. Buffalo Soc. Nat. Sci., 19, No. 2, pp. 16-21. 88 FIELDIANA: GEOLOGY, VOLUME 10 ROEMBR, F. 1854. Lethaea geognostica. Stuttgart. 1860. Die silurische Fauna des westlichen Tennessee. Breslau. 1861. Die fossile Fauna der silurischen diluvial-Geschiebe von Sadewitz bei Oels in Nieder-Schlesien. Breslau. Schluter, C. 1885. Octacium rhenanum, n. gen. et sp. Sitzungsberichte der niederrheinischen Gesellschaft fur Natur- und Heilkunde in Bonn. Thompson, D'Arcy W. 1942. On growth and form. Cambridge. Wells, J. W. 1943. A new species of Astraeospongia from the Middle Devonian of Ohio. Ohio Jour. Sci., 43, pp. 210-211.