yune 24, 1875] 



NATURE 



59 



48 



—On Prorastomus strenoidesy Owen. (Part II.), by Prof. Owen, 

 F.R.S. The author has submitted the skull of a Sirenian from 

 Jamaica, described by him in 1855 under the name o\ Prorastomus 

 siroio'ides, to a careful re-examination ; and in this paper 

 notices the characters revealed by further removal of the matrix, 

 and discusses the bearings of the facts thus ascertained upon the 

 relations of the animal and of the Sirenia generally. The parts 

 ■which have been brought to light are the base and roof of the 

 cranium, the zygomatic arches, the hind half of the mandible, 

 with the articular part of the condyle, and the greater part of the 

 atlas. The characters presented by these parts are described in 

 detail, and the characters of the genus are compared with those 

 presented by other genera of Sirenians, both living and fossil, 

 especially Manaiits and Felsinotherium. The dent^ formula of 

 Prorastomus is given as — 



/. 3-3 d. or c. 1=1, p. 5l=S ^,. 3z:3 

 3—3? I— I ^ 5—5 3-3 



thus, as in Manatus, showing an excess in the molar series over 

 the type of the terrestrial herbivorous mammalia, whilst the 

 incisors and canines retain the common type as to number and 

 kind, and have not been subjected to so great a degree of sup- 

 pression or of individual excess of development as in existing 

 Sirenians. The presence of these small subequal incisorsin both 

 jaws of P7vrastotnus is the most marked feature in which Proras- 

 tomus adheres to the normal mammalian type, while showing 

 the essential characters of the marine Herbivores ; but a similar 

 tendency is shown in other parts of the skull. The author regards 

 the Sirenia as essentially monophyodont. Halicore and Felsino- 

 therium depart further from the type than Halitherium and 

 Manatus, a.ni\.htse Xhz.x\ Prorastomus. Rhytina, with a better 

 developed brain and with the jaws edentulous when adult, is an 

 extreme modification of the Sirenian type. The rudimentary 

 femur in Halitherium is to be regarded as the result of degenera- 

 tion through lack of use, from better-limbed prototypal mammals. 

 AVith respect to the genealogy of the Sirenia, the author remarks 

 that Hackel derives the Sirenia, Zeuglodontes, and Cetacea, to- 

 gether with the Artiodactyla, from the branch Ungulata, and the 

 Perissodactyla from the branch Pycnoderma of the Mammalian 

 trunk ; but that while Halitherium and Felsinotherium show the 

 molar pattern of Hippopotamus, Prorastomus exhibits that of 

 Lophiodon and Tapirus, to which Manatus also adheres rather than 

 to any Artiodactyle type. The author suggests that both Ungu- 

 lates and Sirenians diverged at some remote period from a more 

 generalised (cretaceous ?) mammalian gyrenceplialous type ? and 

 that the marine Herbivora in the course of long Eocene and 

 Miocene eons were subjected to conditions producing modifica- 

 tions of their molars, leading on one side to an Artiodactyle and 

 on the other to a Perissodactyle character. As Prorastomus by 

 its more generalised dentition and shape of brain represents a 

 step nearer the speculative starting-point than any other Sirenian, 

 it acquires a great interest, and the determination of the precise 

 age of the (supposed Eocene) bed from which its remains were 

 derived is very much to be desired. — On the structure of the 

 skull of Khizodus, by L. C. Miall, F.G.S. In this paper the 

 author described a large skull of Khizodus from the coal-shale of 

 Gilmerton, near Edinburgh. The characters described show 

 that Rhizodus is a Ganoid fish, and that its position in the 

 order is not far from Holoptychius and Megalichthys. The 

 author referred it to the cycloidal division of ihe family Glypto- 

 dipterini. — Appendix to a note on a modified form of Dinosaurian 

 Ilium, hitherto reputed Scapula, by Mr. J. W. Hulke, F.R.S. — 

 This paper contained a notice of the pubis of Iguanodon, which 

 proves to be identical with the smaller of the two specimens 

 figured by the author in a former paper (Quart. Journ. Geol. 

 Soc xxx. pi. xxxii. Fig. i). When inverted, its long slender 

 process is easily identified with that of the pubis of the nearly 

 allied Hypsilophodon, and this slanted downwards and back- 

 wards parallel to the ischium, the little process of its posterior 

 surface, meeting a corresponding process of the ischium, and con- 

 verting the upper end of a long narrow obturator space into a 

 foramen. The pubis of Iguanodon contributed largely to the 

 formation of the acetabulum, thus resembling that of existing 

 Lacertilia, as also in its possession of a broad ventral extension, 

 probably united with that of the opposite side by a median 

 symphysis. The specimens described in this paper were col- 

 lected in the Isle of Wight by the Rev. W. Fox. — Notes on the 

 Paleozoic Echini, by Mr. Walter Keeping, of the Woodwardian 

 jMuseum, Cambridge; communicated by Prof. T. M 'Kenny 

 Hughes, F.G.S. The author alluded to the interest excited by 

 the discovery of Echinoderms with flexible tests ; and having 



pointed out the dSficrcnce between the more modern and the 

 Paloeozoic forms (their plates imbricating in opposite directions), 

 gave a description of the following forms :— (i) Perischodomus*; 

 (2) Ra:chtnus, g. n. , sp. K. irregularis (Keeping) ; (3) Pal.cchinus (?) 

 intermedius (Keeping) ; (4) Palachinus gigas (McCoy) ; (5) Pa- 

 hcchinus sphcericus (McCoy) ; (6) Archaocidaris Urii (Fleming). 

 In conclusion, the author proposed a new method of classification 

 for the Echinoidca. He also noticed the existence in the Mu- 

 seum of the Royal School of Mines of a British fossil which 

 appears to belong to the group of Echinoidea with numerous 

 ranges of ambulacral plates, represented in America by the 

 genera Melonites, Oligoporus, and Lepidesthes.— On some fossil 

 Alcyonaria from the Australian Tertiary deposits, by Prof. 

 P. Martin Duncan, F.R.S. In a former communication 

 in 1870 the author described some fossil corals from the 

 Tertiary strata near Cape Otway, in the province of Victoria. 

 In one, which he called the " Upper Coralline bed," the equiva- 

 lent of the Polyzoan limestone of Woods, he found specimens 

 which he did not then describe, as they were not true corals. 

 Belonging to the Isidinae, and not being of great interest, he 

 retained them until the receipt of some similar specimens from 

 New Zealand, described m the following paper. The Austra- 

 lian forms described by the author were shown to be nearly allied 

 to the recent Isis Iiippuris and the fossil /. corallina. — On some 

 fossil Alcyonaria from the Tertiary deposits of New Zealand, by 

 Prof. P. Martin Duncan, F.R.S. The New Zealand fossils re- 

 ferred to in the preceding paper were sent to the author by Capt. 

 F. W. Hutton, F.G.S. ; they were derived from the Awawoa 

 Railway cutting, and were from the upper part of the Oawaru 

 formation. They consisted of fragments of species of the genus 

 Isis and of Corallium. These were compared with those from 

 the Australian Tertiaries, and the author inferred that both 

 deposits were formed under similar conditions, and that they 

 were at least homotaxial, whatever their precise geological age 

 might be. — On some fossil corals from the Tasmanian Tertiary 

 deposits, by Prof. P. Martin Duncan, F.R.S. The author de- 

 scribed a new species of Dendrophyllia possessing very unusual 

 characters, the epitheca replacing the true wall, and giving the 

 specimen a marked Palaeozoic appearance. The fossil was ob- 

 tained from a Tertiary deposit, and was associated with Place- 

 trochus deltoideus, a well-marked coral, characteristic of a definite 

 geological horizon in Victoria, namely, the lower beds of the 

 Cape Otway section, belonging to the Lower Cainozoic period. 

 For this coral he proposed the name oi Dendrophyllia epithecata. 

 A much worn reef-coral was found associated with the above. 



Meteorological Society, June 16.— Dr. R. J. Mann, presi- 

 dent, in the chair. — The following papers were read :— On a 

 white rain or fog bow, by Mr. G. J. Symons. — On a proposed 

 form of thermograph, by Mr. Wildman Whitehouse, F.R.A.S. 

 — On the rainfall at Athens, by Prof. V. Raulin (translated by 

 Mr. R. Strachan). These observations were made by M. Julius 

 Schmidt, director of the Greek Observatory, and embrace a 

 period of twelve years and a half, viz., from August 1859 to 

 December 1871. The average yearly fall is 15 83 inches, and 

 the average number of wet days ninety-three. The wettest year 

 was 1864, when 28*30 inches fell, and the driest 1862, with 9 63 

 inches. — On the barometric fluctuations in squalls and thunder- 

 storms, by the Hon. Ralph Abercromby. There are two classes 

 of storms in this country : in one the barometer rises, in the other 

 it falls. The author in the present paper only refers to the 

 former. After mentioning some of the phenomena which accom- 

 pany storms of this class, he proceeds to give two instances as 

 typical of their general character. In conclusion he makes the 

 following remarks on their origin : — Though in this country 

 squall-storms are almost always associated with primary or 

 secondary cyclones, those in India and Africa are not connected 

 with cyclones, and hence the source of the barometric rise 

 cannot be due to any special phenomenon of cyclone motion. 

 Since the rise is always under the visible storm, it is propagated 

 at the same rate and in the same manner as thunderstorms. 

 Enough is known of the course of the latter to be certain that 

 they art not propagated like waves or ripples, and hence these 

 small barometric rises are not due to aerial waves, as has some- 

 times been suggested. Since the general character of the rise 

 is the same whether there is thunder or not, it is evident that 

 electricity, even of that intensity which is discharged disruptively, 

 is not the cause of the rise. If we look at a squall from a dis- 

 tance, we always see above it cumulus, which is harder and 

 more intense in the front than in the rear of the squall. Since 

 cumulus is the condensed summit of an ascensional column of 



