378 PROCEEDINGS OP SECTION C. 



in 1882, described (c) a nodular organism found in great abundance in 

 the limestones of Indiana, belonging to the Cincinnati gioup (Upper 

 Ordovician). The nodules described by Miller have an average 

 diameter of about a centimetre, and consist of " numerous irregularly 

 concentric, more or less wrinkled, calcareous laminae, separated by 

 interlaminar spaces filled with minute vertical tubes." These fossils 

 had already been noticed by Dr. J. T. Plummer. who, in a 

 communication to the American Journal of Science, referred to them 

 as " pisolitic balls embedded in the solid rock," and stated that 

 the pisolite stratum varied from 2ft. to 10ft. in depth. To these 

 nodules Miller gave the name Stromatocerium richmondense, believing 

 it to be a stromatoporoid referable to J. Hall's genus. Some years 

 later Professor Nicholson received examples of fossils regarded as 

 " S. richmondense " from Mr. E. 0. Ulrich, and, from a microscopical 

 examination of these, concluded that they belonged partly to the genus 

 Girvanella. but of a species distinct from G. problematica, as shown by 

 their smaller tubules (d). At the same time Nicholson pointed out 

 that some of the associated nodules were of an entirely different charac- 

 ter, being of a more compact and uniform structure, and referable to 

 Solenopora compacta, Billings. 



Dr. G. J. Hinde, in 1887, (e) drew attention to the identity with 

 Girvanella of the supposed calcareous sponge described by Professor 

 H. M. Seeley,(/) in 1885, as Strephochetus ocellatus, which occurs in the 

 Chazy limestone (Lower Ordovician) of North America. Nicholson 

 also was satisfied as to the Girvanella relationship of this organism, 

 and expressed the opinion that it may probably be specifically distinct 

 from G. problematica. (g) Hinde further showed {loc. cit.) that Dr. 

 Bornemann's then recently described genus Siphonema, represented 

 by small rounded masses like nuUipores, and consisting of a bundle of 

 minute curved tubes, is likewise identical with Girvanella. These little 

 nodular bodies, occurring in some abundance both in the Gotlandian 

 (Silurian) limestones of the Baltic and in the Cambrian limestones of 

 Sardinia, were regarded by Bornemann as calcareous algse, and allied 

 to living, subferial forms. Nicholson, in 1888, (A) further noticed some 

 organic remains in the Carboniferous limestone of the North of England, 

 which, although ill-preserved, were thought to be referable to Girvanella. 



The Jurassic beds of England yielded very interesting results Avith 

 regard to Girvanella in the hands of Mr. E. Wethered, for he showed, 

 in 1889, (z) that certain pea-grits in the Corallian and Inferior Oolite 

 were largely due to the encrusting tubules of that little organism 

 enveloping detrital organic fragments derived from echinus spines, 

 polyzoa, crinoids, molluscan shells, and foraminifera. One of the 

 most characteristic forms Wethered named G. pisolitica. In another 

 paper, read before the Geological Society in 1889,(;;') the same author 

 brought forward further interesting evidence as to the occurrence of 



(c) Miller ('82), pp. 41, 42, pi. il., figs. 1, la, b. (d) Nicholson ('88), p. 24. 

 (e) Hinde ('87), p. 227. (/) Seeley ('85), p. 355. (g) Nicholson ('88), p. 24. 

 (h) Nicholson ('88), p. 24. (i) Wethered ('89), p. 196. (j) Wethered ('90), p. 270. 



