86 



NA TURE 



[May ?8, 1896 



when repeated at intervals and compared. The scale of these 

 photographs is 3 "4 times as large as that of Klein's Star Atlas, 

 and the area of any region is 11 '5 times larger. This is some- 

 what smaller than Argelander's charts. 



The multiple star S Orionis, a single star to the naked eye, is 

 well shown as three stars, one of which is much elongated, 

 showing the duplicity of that component ; a curious S-shaped 

 group of stars is clearly seen between S and e. These are quite 

 invisible to the naked eye. 



Fig. 3 represents the Pleiades as photographed with si.\ty 

 minutes' exposure. In the region shown, ordinary keen eyes see 

 only seven stars. On the negative seventy-eight stars can be 

 counted in a space of 3" square in the centre of this region. 

 These include stars of the eleventh magnitude. 



As regards the actual driving of the telescopes, very little 

 practice is needed ; a gentle pressure of the finger at the lower 

 end of the base-board carrying the objective and plate, is 

 sufficient to move the telescope at the proper rate, and the 

 co-operation of hand and eye during guiding seems soon to 

 become almost automatic in character. When the instruments 

 are stationary, the image of the star used for guiding, apparently 

 travels many times faster than does the image of the star on the 

 plate, owing to the magnification by the eyepiece ; and for this 

 reason any tendency to error in driving can be readily seen, 

 especially with the enlarged star disc divided into four quadrants 

 by crossed hairs in the eyepiece — long before such an error would 

 be appreciable on the plate itself. 



With the lens used, which was made by Hilger, and is 

 uncorrected for photography, a field of good definition 5" square 

 could readily be obtained. 



An ordinary portrait lens of 2j-inch aperture, mounted side by 

 side with the 3j-inch refractor, gave very good results. One 

 photograph of the Hy^des, taken by its means, showed Neptune 

 very distinctly. 



The wooden dew-cap was found remarkably effective in 

 keeping the object-glass clear, even when that of the guiding 

 telescope, provided with a metal dew-cap, became bedewed. 



When amateurs come to recognise that, with their small 

 instruments, such a fruitful field for investigation is open to 

 them, astronomy will probably be enriched by many discoveries 

 which would otherwise be missed or delayed. 



Joseph Lunt. 



THE EXTINCT VERTEBRATES OF 

 ARGENTINA} 

 T^HE fossil vertebrata of South America are of peculiar interest 

 to English paUeontologists, since much of our earlier 

 knowledge of the extinct mammals of that region is due to col- 

 lections sent to this country by Sir Woodbine Parish and 

 Darwin, and de.scribed by Owen, Clift, and others. These col- 

 lections, however, valuable as they were, gave no idea of the 

 extraoidinary variety and abundance of the extinct fauna, the 

 full importance of which has only been recognised of late years. 

 The terrestrial Mammalia of South America are, perhaps, the 

 most remarkable and most strictly autochthonous in the world. 

 If we except some marsupials as possibly Australian types 

 and some comparatively recent immigrants, the whole of the 

 mammals are peculiar. The American Edentata form a dis- 

 tinct order (for there is no reason for associating the Old 

 World Manida; and Orycteropidre with them), and until the 

 Upper Miocene (Loup Fork), they are entirely confined to the 

 southern half of the continent. The other great divisions of 

 the Mammalia are either represented by peculiar sub-orders or 

 families, or, as in the case of the Insectivora, are entirely absent. 

 Remains of this remarkable fauna are found in deposits of several 

 horizons, which, in the wealth of species and individuals they 

 contain, can only be compared to the Tertiary lake-basins of 

 North America. In some cases the series seems to be sufficiently 

 complete for the history of certain of the groups to be, at least 

 partly, worked out, and it is to be hoped that the study of the 

 development of these isolated types, taken in conjunction with 

 the already clearly determined phylogenetic history of many 

 North American groups, may lead to important generalisations 

 as to the laws in accordance with which mammalian evolution 

 has advanced. Unfortunately, up to the present, much less 



1 " Contributions to a Knowledge of the Fossil Vertebrates of Argentina." 

 Parts I. and U. By R. Lydekker, F.k.S. {Aiiales del Museo dc la Plata, 

 " Palieontologia Argentina, 11. and III.) Folio, La Plata. 189.V4. 



NO. 1387, VOL. 54] 



attention has been paid to points of morphological interest than 

 to the making of new genera and species, many of which are 

 founded on quite insufficient evidence, the result being that the 

 nomenclature h.as been brought into an almost unparalleled state 

 of confusion. It was with the intention of clearing up simie of 

 this confusion that, at theinvitationof Dr. Moreno, Mr. Lydekker, 

 in 1893-94, paid two visits to the La Plata Museum. The brief 

 time at his disposal rendered it impossible for him to carry out 

 his object with complete success, but he has nevertheless produced 

 a work of the highest value, both from the purely original matter 

 it contains, and also because it renders easily accessible descrip- 

 tions and good figures of many little-known forms. Moreover, 

 he has earned the gratitude of all students of mammalian 

 palaeontology by relegating to the synonymy a large number of 

 imperfectly defined genera and species. 



The first of the two volumes contains three memoirs, two of 

 which consist of descriptions of new material, while the third is 

 occupied by a revision of the Ungulata. The second, with the 

 exception of a few supplementary pages on the Ungulates, and 

 descriptions of two new species ofCarnivora, is entirely devoted 

 to the Edentata. 



In the first memoir are described some Dinosaurian remains 

 from Patagonia, the first recorded from South America. The 

 most completely known form is a member of the Sauropodous 

 group ; it is referred to the genus Titanosaurus, species of 

 which also occur in the Wealden of the Isle of Wight and in the 

 Lameta beds of Central India ; but since these are only known 

 by caudal vertebrse, it seems very doubtful whether there is 

 sufficient evidence to establish the generic identity of the South 

 American species with them. Nevertheless the existence of a 

 gigantic Sauropodous Dinosaur in Patagonia is certain : and this 

 fact, together with the recently recorded discovery of a member 

 of the same group in Madagascar, shows that these reptiles had 

 extremely wide range during Jurassic and Cretaceous times in 

 both the northern and southern hemispheres. 



The second memoir deals with a number of Cetacean skulls 

 from Patagonia. These are of great interest, both on account 

 of the light some of them throw on the history of the group, and 

 also because they show that the Santa Cruz beds are certainly 

 later than the Eocene (to which they are assigned by the Argen- 

 tine writers), and are probably Miocene. Physodon, a genus 

 previously known only from teeth occurring in the Miocene and 

 Pliocene of Belgium and P^ngland, and probably ancestral to 

 the sperm whales (Physeter), is represented by Physodon pala- 

 goniciis, which possessed a series of teeth in the upper jaw ; 

 these have entirely disappeared in the recent form. Another 

 interesting species is Prosi/iia/odoii atislrak, a Squalodont re- 

 markable for the small number of its molars and for its com- 

 paratively well-developed nasals, characters in which it ap- 

 proaches the Eocene Zeuglodonts more nearly than any toothed 

 whale previously known. A primitive type of the I'lalanistidce 

 is also described. This memoir is an important addition to the 

 history of the Cetacea, for although, as might have been ex- 

 pected from the age of the deposits, no light is thrown upon the 

 difficult question of the origin of the group, the author is to be 

 congratulated on having helped to fill some of the gaps in our 

 knowledge of it. 



The South American Ungulates appear to suffer from an 

 extraordinary superfluity of names. Mr. Lydekker regards no 

 less than ten generic terms as synonymous with Nesodon, and 

 states that the number of specific names that have been applied 

 to Nesodon inibricalus is countless. In the classification of the 

 order the most important innovation is the establishment of a 

 new sub-order, the Astrapotheria, for the reception of the 

 Homalodontotheriidce and the Astrapotheriida;. It is suggested 

 that the European genus Cadurcotherium may belong here ; this 

 seems very improbable, but if true is one of the most remarkable 

 facts of distribution known. In the description of Astrapo- 

 therium there seems to be some doubt as to the nature of the 

 immense upper tusks, since in one place they are said to be 

 canines, while in the dental formula given they are put down as 

 incisors. The suborder Litopterna, adopted for the reception 

 of the Proterotheriidfe and Macraucheniid^u, is regarded by the 

 author as being intermediate between the Astrapotheria and the 

 Perissodactyla, though not ancestral to the latter. Indeed there 

 can be no doubt that the peculiar foot-structure of the Litop- 

 terna was acquired quite independently of the Perissodactyla, 

 and that such points of resemblance as exist between them are 

 merely due to parallelism of their lines of evolution, a cause of 

 similarity often neglected. 



