July 14, 1892] 



NATURE 



'57 



present discovery is of great interest as extending still further 

 the ascertained geographical range of the genus during 

 Cretaceous times. 



The very extensive alterations in botanical nomenclature 

 proposed in Kuntze's " Revisio Generum " has prompted a 

 proposal, emanating from the four eminent German botanists, 

 Ascherson, Engler, Schumann, and Urban, with the assent of 

 a number of their colleagues, for a revision of De CandoUe's 

 " Lois de Nomenclature Botanique." The essential points of 

 the propositions are that the starting-point for the priority of 

 genera, as well as of species, shall be the year 1753, the date of 

 the publication of Linnaeus's "Species Plantarum " ; that 

 ' ' nomina nuda " and " semi-nuda, " i. e. names without a diagnosis, 

 or with only a very imperfect diagnosis, shall be rejected, as well 

 as figures without a diagnosis ; that no generic name shall be re- 

 jected because of its similarity to another generic name, even if it 

 differ only in the last syllable, but that, if the difference be in 

 spelling only, the later name must be rejected ; that the names 

 of certain large and universally known genera be retained, even 

 though they would have to be rejected by the strict rules of 

 priority. English botanists are invited to signify their assent 

 or otherwise to these propositions. 



At the meeting of the Linnean Society of New South Wales, 

 on May 25, Mr. Pedley exhibited a very fine and perfect saw, 

 about 5 feet long, of the saw-fish Pnstis zysron, Bleeker. The 

 fish, without the saw, was about 19 feet long, and was captured 

 in a net at Evans River, N.S.W. The number of pairs of 

 rostral teeth for this species is usually given as from 26-32 ; the 

 specimen exhibited had only 25 pairs, all in place. At the 

 same meeting, Mr. Hedley exhibited, on behalf of Mr. 

 Rainbow, a spider of the family EpeiridiE. This rare and re- 

 markable insect furnishes an addition to the fauna of Australia, 

 and it is supposed that a new genus may be required for its 

 reception. 



Mr. W. a. Rogers, writing to Science from Colby Univer- 

 sity, Waterville, Me., confirms testimony given by Mr. Kunz 

 as to the fact that the hardness of diamonds is not perceptibly 

 reduced by cutting and polishing. In the earlier years of Mr. 

 Rogers's experience in ruling upon glass he was accustomed to 

 select a gem with a smoothly-glazed surface, and, the stone 

 being split in a cleavage plane inclined at a rather sharp angle 

 to the natural face selected, this split face was ground and 

 polished. In this way he was able to obtain at several points 

 short knife-edges, which gave superb results in ruling. It was 

 soon found, however, that after ruling several thousand rather 

 heavy lines the diamond was liable to lose its sharp cutting- 

 edge, and this experience became so frequent that he was com- 

 pelled to resort to the method now employed, that of grinding 

 and polishing both faces to a knife-edge. He has one ruling 

 diamond prepared in this way, which has been in constant use 

 for four years, and its capacity for good work has not yet been 

 reduced in the slightest degree. A diamond prepared by Mr. 

 Max Levy, of Philadelphia, has given even better results, and 

 so far it shows no evidence of wear. 



The Bulletin de la Socieli des Naturalistes de Moscou 

 (1891, Nos. 2 and 3) contains a very interesting paper, in 

 French, by Prof. A. Pavloff and Mr. G. W. Lam pi ugh, on 

 the Speeton clays and their equivalents. These clays, which 

 have long occupied the attention of geologists, have ac- 

 quired of late a new interest owing to close resemblance 

 between their fauna and that of similar deposits in other 

 countries, even as far distant as Russia. The work consists of 

 three parts : the first part, devoted to the description of the 

 Speeton clay? and their Lincolnshire equivalents, has been 

 written by Mr. Lamplugh, and will, no doubt, be published in 

 NO. I 185, VOL. 46] 



English as well. The second part, by Prof. Pavloff, is devoted 

 to the description of the Cephalopods found in these clays, the 

 Speeton forms being compared with those of other countries, 

 and especially those of Russia. A table giving the succession 

 of the subdivisions of the Jurassic and Cretaceous deposits, with 

 their leading fossils, in the two Russian localities where they 

 are best represented (Moscow and the lower Volga), is given 

 by the author, and it differs from a previous table by the intro- 

 duction of a new series, named Petchorian, which, although it 

 has the thickness of but a few inches, has nevertheless a very 

 peculiar fauna, of a well-determined character. However, for 

 the present it is not possible to classify it either under the 

 Jurassic or the Cretaceous formation. The table is followed by 

 a detailed description of twenty-five species of Belemnites, 

 of which eight are new, the chief interest of this description 

 being in the attempt to give in each case the genealogical rela- 

 tions of closely allied species, and in a special chapter devoted 

 to the geological history of Belemnites generally and the de- 

 scent of various species supposed to have originated from the 

 Belemnites tripartitus of the middle Jurassic and Lias epoch. In 

 a subsequent paper, which will contain the third part of the 

 work — namely, a comparison of the Speeton clays with those of 

 other localities — the author proposes to describe in the same 

 way the Speeton Ammonites, which are even more interesting: 

 than the Belemnites ; and he hopes to be able then to give a 

 more positive answer as to where the separation must br 

 taken between the Jurassic and the Cretaceous deposits of the 

 Speeton clays and analogous deposits. 



Mr. Matthias Dunn writes to us from Mevagissey, Corn- 

 wall, that the fishing-boat Mispah landed a large shark there 

 lately which had got entangled in her mackerel nets. Its length 

 was II feet 2 inches, and in its stomach were two considerable- 

 sized congers. The creature proved to be Couch's Ponbeagle 

 Shark, or Lamna cornubica of Cuvier. 



The additions to the Zoological Society's Gardens during the 

 past week include a Tiger {Felis tigris i jr.) from Amoy, 

 China, presented by Mr. Robert Bruce ; two Mountain Ka-kas 

 {Nestor notahilis) from New Zealand, presented by the Earl of 

 Onslow, K.C.M.G. ; a Chilian Sea Eagle {Geranoaetus melano- 

 leucus) from Chili, presented by Mr. Edward Jewell ; a Broad- 

 fronted Crocodile (Crocodiltis fron'atus) from West Africa, 

 presented by Mr. G. T. Carter ; a Common V>02.{Boa constrictor) 

 from South America, presented by Mr. A. E. Oakes ; a Macaque 

 Monkey {}Aacacus cynomoli^us 9) from India; a Kinkajou 

 {Cercoleptes candivolvulus) Iroxa Demerara, deposited; a Hippo- 

 potamus {Hippopotamus ainphibius <5 ) bred in Antwerp ; sixteei' 

 Common Boas {Boa constrictor) from South America, purchased ; 

 an Indian Muntjac {Cervulus muntjac i ) born in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



Lunar Photography.— Dr. L. Weinek, of the Pragu • 

 Observatory, has been the recipient of several photographs <>' 

 the moon from Prof. Plolden for the purpose of making enlarge 

 ments from them. The photographs were obtained with th • 

 large equatorial of the Observatory at Mount Hamilton, and an 

 illustration of one of the enlargements is given in L'Astronomir 

 for July. The photograph is of the large crater Petavius, 153 

 kilometres in length. With M. Wcinek's apparatus the photo 

 graph was enlarged twenty times, giving a lunar image of nearly 

 three metres in diameter. At first sight the photograph look- 

 as if the enlargement had been carried a little too far, but when 

 held at arm's length the effect is very fine. The most striking 

 features noticeable are the narrow river-like lines, which are 

 numerous and very alike in appearance. Whether these are 

 really photographic or not of course we cmnot say, as we have 

 not seen the original negatives, but they seem to be rather too 



