JRevieics — Karpiiinhy on Ilelicoprion. 33 



The Oidovieian chert of Chypou's Farm, in Mullion parish, 

 continuous with the Eadiolarian chert of Mullion Island, was 

 examined in 1899, and yielded : Spheeroidea, 3 genera (with 3 

 species) ; Prunoidea, 3 genera (G species) ; and Discoidea, 1 genus 

 (1 species). 



Dr. Hinde's latest memoir on Radiolaria has been prepared as an 

 Appendix for the " Geology of Central Borneo," to be published by 

 Professor Dr. G. A. F. Molengraaf, of the Dutch Exploring Expedi- 

 tion, in 1893-4. In his Introduction Dr. Hinde describes tho 

 outcrops and general character of the Eadiolarian rocks under 

 notice, namely, jaspers, cherts, hornstone, and diabase tuff. Their 

 local occurrence in the siliceous rocks and in the tuffs, and the dis- 

 tribution of these fossil Eadiolaria in other countries, are indicated 

 in the table at pp. 44:-4G, and treated in detail in the text : — 



Genera. Species. 



Bcloklca ... ... ... 1 ... ... ... 1 



8ph(sroidca ... ... ... o ... ... ... 17 



Friowidca ... ... ... 5 ... ... ... 12 



Discoidea ... ... ... 6 ... ... ... 16 



Cijrtoidca 13 54 



30 100 



These rocks are stated to underlie sti-ata of Cenomanian age, 

 and they seem to belong either to the latest Jurassic or the earliest 

 Cretaceous age, as is the case also with the Eadiolarian cherts and 

 jaspers of the Coast Eange in California, 



Great services have been rendered to geology by Dr. Hinde's 

 elucidation of the relics of some very obscure Invertebrata, in his 

 successful studies of the Silurian Conodonts, of Sponges of every 

 group and age, and now of Palaeozoic and other Eadiolaria. He has 

 thus indicated how the relative age of many rocks may be deter- 

 mined by the evidence of several kinds of microscopic fossils. 



II. — Helicopriox — Spine or Tooth ? 



" Ueber die Eeste von Edestiden und die neue Gattung Helicoprion.''' 

 By A. Karpinsky. Vei'handl. k. russ. min. Ges. St. Petersburg, 

 ser. II, vol. xxxvi, No. 2, with 4 pis. and 72 text-figs. (1899). 



PALEONTOLOGISTS are indebted to the eminent Director of 

 the Imperial Eussian Geological Survey for one of the most 

 exhaustive memoirs on a fossil ever published. Dr. Karpinsky's 

 description of the strange ' ichthyodorulite,' Helicoprion. is a model 

 of what such a work should be — thorough from every point of view, 

 geological, chemical, and biological. It is, moreover, illustrated by 

 exquisite plates, besides numerous text-figures, representing not 

 only the outward form of the problematical fossils dealt with, but 

 also every feature of their microscopical structure. 



Helicoprion, to a superficial observer, looks much like an 

 ammonite ; but on closer inspection it is easily recognizable as 

 a spiral consisting of teeth firmly fixed together by their bases. 

 Fragments of a more or less similar spii'al have ah'eady been 



DECADE IV. VOL. VII. — NO. I. 3 



