BIBLIOGRAPHY. 35 



191. 1881 Waloott, C. D. On the Nature of Cyathophycus (Amer. Journ. Science, 



vol. 22, p. 394). 

 Its structure is stated to consist of narrow bands forming a horizontal 

 and a perpendicular series, which cross each other at right angles. The bands 

 are composed of threadlike spicula, now of pyrites. Two species are described. 

 No reference is made to the form of the individual spicules beyond that they 

 are threadlike. 



192. 1881 Steinmann, G. Ueber ProtetraclisLinhi, n. f. eine Lithistide des Malms 



(Neues Jahrbuch, Bd. ii, pp. 154—163, PI. IX). 

 Describes a lithistid in which there is considerable variety in the form of 

 the skeletal spicules. It is regarded as a genuine Tetracladine. The author 

 also refers the Silurian genus Aulocopium to the same family. 



193. 1882 Hinde, G. J. Notes on Fossil Calcispongice, with descriptions of new 



species (Ann. and Mag. Nat. Hist., vol. x, pp. 185 — 205, Pis. X — 



XII). 

 Records the discovery in fossil Pharetrones, from the Upper Greensand, of 

 three- and four-rayed spicules, which can be detached from the matrix, and are 

 clear-ly identical in form with those of recent calcisponges. Some of them 

 also occupy a similar relative position on the dermal surface of the Sponge. 

 A specialised three-rayed spicule, in the shape of a tuning-fork, is present in 

 the fossil genus Sestrostomella ; it closely resembles a spicule in an existing 

 Australian calcisponge. These facts clearly establish that the Pharetrones 

 are, as Zittel claimed them to be, true calcisponges. 



194. 1882 Steinmann, G. Pharetronen-Studien (Neues Jahrbuch, Bd. ii, pp. 139 — 



191, Pis. VI— IX. 

 This paper, which appeared almost simultaneously with that by Hinde 

 mentioned above, contains the results of the author's five years study of the 

 group. The Pharetrones are regarded as having been originally calcareous, 

 their spicular elements are stated not to resemble those of recent calcispouges, 

 since, amongst other reasons, no axial canals can be detected in them, and the 

 recent spicules are stated to be so delicate as readily to melt in distilled water 

 in a few seconds. Their structures are finally compared to those of Alcyonaria. 

 Subsequent investigations have shown that the author's theories respecting 

 the group are altogether erroneous. 



195. 1882 Zittel, K. A. Notizen iiber fossile Spongien (Neues Jahrb., ii Bd., 



p. 203). 

 Confirms Hinde's observations on the spicular structure of Gorynella and 

 other Pharetrones, and regards their character as calcisponges to be fully 



