HARDWICKE'S SCIENCE-GOSSIP. 



little volume under notice there is a special chapter 

 on "The Ferns round London," which will be very 

 useful to those who are eager to grub these pretty 

 plants up. 



Ocean Currents and the System of the World, by 

 W. L. Jordan (London : Longmans). The author is 

 a bold, ingenious, learned, and irrepressible physical 

 geographer — one who is well aware his confreres do 

 not agree with him, but who has the courage of his 

 convictions, and the fortunate means of publishing 

 them. The present volume is chiefly valuable as 

 containing a full and complete outline of Mr. Jordan's 

 hypothesis. 



The Naturalists 1 World, edited by Percy Lund 

 (London : Swan Sonnenschein & Co.), is the second 

 volume of our pleasant and friendly contemporary, 

 beautifully got up in every way, type, binding, and 

 illustration, so that it will make an acceptable new 

 year's present. 



We desire to recommend the following little 

 manuals : Lectures on Heat, Sound and Light, by 

 Dr. Richard Wormell (London : Thomas Murby) ; 

 Chemical Students' 1 Manual, for the lecture-room and 

 laboratory, by H. L. Buckeridge (London : Thomas 

 Murby). 



We have also received Longitude by Lunar Dis- 

 tances, by Major II. W. Clarke (London: W. H. 

 Allen & Co.), a work of enormous labour ; The 

 Aryan Maori, by Edmund Tregear (Wellington : 

 Geo. Didsbury), a bold and ingenious essay, proving 

 the New Zealanders to be of Aryan origin. If the 

 author's conclusions are accepted, he will have the 

 merit of securing a high position as an anthropologist. 



The Open Air, by Richard Jefferies (London : 

 Chat to & Windus). This handsomely got up book is 

 a collection of some of Mr. Jefferies' most delightful 

 essays, reprinted from various magazines and journals. 

 The author's style has placed his books among our 

 modern classics, and there are few which will be 

 read with greater pleasure than the present volume. 

 The titles of some of the papers alone will convey to 

 the readers who have enjoyed Mr. Jefferies' other 

 bcoks, some idea of their attractive character : 

 "Sunny Brighton," "The Pine Wood," "Nature 

 on the Roof," "The Haunt of the Hare," Under 

 the Acorns," " Downs," "Haunts of the Lapwing," 

 " Beauty in the Country," " On the London Road," 

 &c. <\c. 



GREEN Flies.— Your query in the September 

 number reminds me of the following which I came 

 across in a newspaper about the middle of August, 

 and which, perhaps, may be useful. There was a 

 plague of small green flies at Peterborough on 

 Thursday. For an hour or two in the middle of the 

 day Narrow Street was thick with them. In some 



places they fell on the ground an inch thick. 



A. G. S. 



CHAPTERS ON FOSSIL SHARKS AND 

 RAYS. 



By Arthur Smith Woodward, F.G.S. 



VI. 



ICHTHYODORULITES. (Continued). 



/I CONDYLACANTHUS is a slender and con- 

 ■*± siderably elongated spine, ornamented with 

 more or less denticulated longitudinal ridges, and 

 having posterior denticles ; it is particularly interest- 

 ing from the fact that its internal cavity opens only 

 at the base, thus perhaps indicating an affinity with 

 the Rays. No species appear to have been hitherto 

 recorded from the upper divisions of the Carbon- 

 iferous series, but Mr. Davis enumerates* seven 

 forms from the lower strata of Armagh and Bristol, 

 and several others occur in Americaf ; the latter first 

 led to the determination of the genus, Agassiz not 

 having before noted its distinctness from the Mesozoic 

 Leptacanthus, and McCoy having also been induced 

 by imperfect specimens to unite it with Ctenacanthus. 

 LepraeanlhusX is a little richly-ornamented ichthyo- 

 dorulite from the Coal Measures ; and Erismacanthus^ 

 (=Cladacanthus, Agassiz, MS.) is a peculiar three- 

 branched type (fig. i) from the Carboniferous Lime- 

 stone of Armagh, very suggestive of the cephalic 

 spines of certain Chimaeroids. 



Among the fossils of the Permian and Trias, there 

 appear to be no fish-spines of an altogether problem- 

 atical nature, but in the overlying Rhaetic Beds 

 there occurs a form whose relationships are still 

 undetermined, and of which numerous fragmentary 

 remains are met with in the well-known strata of 

 Aust Cliff, near Bristol. This constitutes the genus 

 Nemacanthus (Agassiz), and is readily recognised by 

 its laterally compressed shape and striated external 

 surface, with a thick longitudinal ridge of enamel in 

 front, a row of denticles behind, and a few scattered 

 tubercles of the same hard substance on each side 

 towards the upper extremity. Two Rhsetic species 

 are known, the larger, N. monilifer, and the smaller, 

 N. f lifer — both from Aust Cliff— and the genus is 

 further represented in the Stonesfield Slate by a very 

 short form, known as IV. brevispinus. 



The Lias yields another interesting ichthyodorulite 

 that has received the name of Myriacanthus, from the 

 thorn-like shape of the large denticles composing 

 each of the two longitudinal rows with which its 

 external surface is characterised in addition to the 

 scattered small tubercles ; judging from its general 

 shape, and the fact of the internal cavity opening only 

 at the base, it appears to have belonged to an extinct 

 type of Ray, and the original fish must have been of 

 some considerable size, for some of these spines are as 



* Davis, toe. cit., pp. 346-352. 



t St. John and Worthen, " Geol. Surv. of Illinois (Palaeonto 

 logy)," vol. vi. (1875), p. 432. 



% Owen, " Geological Magazine," vol. vi. (1869), p. 481. 

 $ Sedgwick and McCoy, "Pal. Rocks and Foss.," p. 628. 



