Sept. 19, 1872J 



NA TURE 



425 



of tlie moUusca of Greenland range as far south as Gaste Bay. 

 The species which belong exclusively to the deep sea in Canada 

 have a decidedly Scandinavian aspect. 



Preliminary Notiic of Drccigings in Lahe Ontario, by H. 

 .M'eyne Nicholson, M.D., D.Sc. 



In this communication tlie author gave a short preliminaiy 

 pcrount of a series of dredgings carried out in June and July in 

 l,:ike Ontario. With a praiseworthy appreciation of the value 

 of such researches, the Provincial Government of Ontario had 

 placed at the author's disposal a sum of money to be expended 

 in this investigation, and the results had been very satisfactory. 

 The dredgings were carried on partly in a yacht and partly in a 

 small paddle-wheel steamer, and wore prosecuted wholly by 

 h md, the apparatus employed being similar to that used in marine 

 dredging, except that a bag of embroidery canvas was attached 

 outside the ordinary net, an addition rendered necessary by the 

 exceedingly fine nature of the mud at great depths. 



Upon the whole, the results oljtained in Lal<e Ontario agreed 

 very fairly with those obtained in Lalie Superior in 1871, there 

 bting a general conformity in the phenomena observed in both 

 a'cas. The fauna of Lake .Superior, however, so far as deep 



V a'er is concerned, is decidedly richer than that of Lake Ontario, 

 v.hilst some of the more remarkable species discovered in tlie 

 former appear to be altogether absent from the latter. As 

 might have been anticipated, the fauna of Lake Ontario is not 

 ex'ensive, though some forms occur in great profusion. The 

 sliiUow-water fauna is very rich in individuals, and the number 

 of species is quite considerable for fresh water. Beyond eight or 

 ten fathoms, the fauna becomes very scanty ; and when depths 

 of from twenty to fifty fathoms are reached, the list becomes 

 reduced to some Annelides and Amphipod Crustacea. The 

 nature of the bottom, also, at great depths is very unfavourable 

 to life, consisting almost everywhere of a fine impalpable mud or 

 clay, the temperature of which is very low. 



Out of thirty-one forms in all discovered by the author in 

 Lake Ontario, the most interesting were the Annelides and Crus- 

 taceans. The Annelides were very abundant, and consist of 

 species of Xephdis, CUpsinc, Sacnuris, and Chirodrilliis, some of 

 f:e Leeches presenting phenomena of special interest. Of the 

 CiHslacca, the most important is a little Amphipod, which 

 o:cuned plentifully in from thirty to forty-five fathoms, and 



V hich the author identified with the rontoporeia affinis of the 

 S Afedish lakes. This species, and the .Stomapod, Mysis rdicta 

 of Loven, are found in Lakes Wetter and Wener in .Sweden, and 

 it is well known that they have been sujiposed upon good grounds 

 to support the view that these Lakes h.ad been at one time con- 

 nected with the sea. It is, therefore, a very interesting fact that 

 these crustaceans should both have been found in Lakes Michigan 

 and Superior. The Pontoporcia the author had now detected in 

 I, 'ke Ontario ; but it was a curious fact that the Mysis, which is 

 of common occurrence in Lake Superior, should not have been 

 found to occur at all in the dredgings carried on in Lake Ontario. 



On the Flora of Moab, by A. W. Hayne, M.A. 



The 250 plants found in Moab from the Ijeginning of February 

 to the middle of March, belong to 58 natural orders, of which l.iy 

 far the best represented are Leguminosx with 35 species, Com- 

 posita: and Crucifer.x each with 26, and Graminace.-e 23. The 

 lemainder belonged to LiUaceiie, .ScrophulariacejE, Labiatte, Bora- 

 ginaceee, Umbellifer.'e, etc. From tlie greater abundance of 

 springs the Eastern shore of the Dead Sea is comparatively 

 ftrtile. The most conspicuous difference which results is the 

 abundance of the date palm, of wliich on the West only a 

 single clump survives near Jencho. 



On llie Structure and Dr^elopmeiit of Mitraria, by Prof. All- 

 man, F.R.S. 



Several specimens of the remarkable larval form, to which John 

 Miilkr gave the name of J\fitraria, were obtained by Prof. All- 

 man in the Gulf of .Spezzia, and were made the subject of care- 

 ful study of structure and development. -Mecznikoff had recently 

 examined another species of the same form, and the author was 

 enabled to confirm the main result arrived at by him, that 

 Mitraria was the larval form of an annelide. In some funda- 

 mental points, however, regarding the process of development, 

 liis observations did not agree with those of the Russian zoolo- 

 gist ; while in structure there are some important features which 

 have not been described by either Miiller or Mecznikoff, 

 differences whicli may, in some cases at least, depend on actual 

 differences between the species examined. 



The nervous system is well developed, and consists in the 



principal central portion of a large quadilateral ganglion, formed 

 by the union of two lateral ones, and situated on the summit of 

 the transparent dome-like body of. which the larva mainly con- 

 sists. From this two very distinct chords are sent downwards, 

 so as to form a pair of commissures with two small ganglia, which 

 are situated at the opposite side of the alimentary canal. Be- 

 sides these, two other small ganglia exist in the walls of the dome, 

 at the oral side of the great apical g.anglion, and two similar 

 ones at the ab-oral side. These send off numerous filaments, 

 which dive at once into the walls of the dome, while each sends 

 off a long filament to the region where the alimentary canal 

 begins to bend downwards towards its ab-oral termination. The 

 great apical ganglion supports two sessile ocelli, with pigment 

 and lens, and two small spherical vesicles, each containing a 

 clear spherical corpuscle. These last the author regards as audi- 

 tory capsules. 



A system of vessels was also described. This consists mainly 

 of a sinus which surrounds the great apical ganglion, and sends 

 off three branches, which run in a radial direction in the walls of 

 the dome, two lateral and one ab-oral, and appear to open into 

 a sinus which surrounds its base. 



In the progress of development the ab-oral end of the alimen- 

 tary canal becomes elongated in the direction of the axis of the 

 dome, carrying with it the walls of the base of the dome, which 

 are to form the proper body walls of the future worm, and in this 

 way a long cylindrical appendage becomes developed, and hangs 

 from the central point of the base. At first there is no trace of 

 segmentation, and this is subsequently induced on the cylindrical 

 body of the worm by the formation of consecutive annular con- 

 stractions. 



The process of development as observed by the author in the 

 species of Mitraria examined by him thus differs in several points 

 from that observed by Mecznikoff. Among these the most im- 

 portant is that the ventral side of the worm is formed simul- 

 taneously with the dorsal instead of subsequently to it and in- 

 dependently of it, as in tlie case described by Mecznikoff. The 

 development of the worm was not traced to the ultimate dis- 

 appearance of the dome-like body of the larva. 



On the Whales of the Antwerp Crag, by Prof. Van Beneden. 



A brief account was given of the great accumulation of bones 

 of fossil cetacea, or ratlier of whales, whicli are found in the 

 Antwerp Crag, and of which the gi'eater part belong to species 

 new to science. These primitive whales were all small in size, 

 and in that respect have no existing representative except the 

 Neobala;na of New Zealand. It is only in the Upper Crag that 

 we find representatives of larger species which actually exist such 

 as those of the genera of llakvna, Megaptera, and BahTnoptera. 



Prof Flower said that the excavations at -Vntwerp had revealed 

 a perfect cetacean burial ground. Under the superintendence of 

 a .(-(zrw;;/ who had a most intimate acquaintance with the osteology 

 of recent whales, the skeletons of the extinct species had been 

 almost reconstructed in the Brussels Museum. It was a re- 

 markable thing that these ancient whales were all small. It was 

 the reverse of what happened in most other cases where the 

 ancient representatives of any type were generally far larger than 

 those at present existing'. 



Mr. Sclater i-quired what was the relation between the cetacea 

 of the Antwerp and Suffolk Crag. 



Prof. Van Beneden replied that they were identical. The 

 English material was not in itself sufficient for independent 

 determination ; but with the knowledge he had acquired from 

 the more perfect remains, he was able to identify those from the 

 .SuflTolk Crag. 



Prof AUman said that there was a parallel to the case of the 

 whales in the dwarf fossil elephant of Malta. This was of the 

 more interest, as the affinities of the elephant and of the whale 

 are by no means remote. 



On some points in the Development oj Vortieellide, by Prf 

 AUman, 



The author described, in a beautiful branched and clustered 

 vorticeUid.an, a process different from any which had been re- 

 corded by those observers who had described the so-called en- 

 cysting process, and the behaviour of the "nucleus" intheVorti- 

 cellida;. 



In almost every cluster some of the zooids composing it had 

 become greatly altered in form. They had increased in size, 

 and instead of the bell-shaped fonn of the others had assumed a 

 globular shape, and had lost both oral orifice and ciliary appara- 

 tus, while their supporting peduncle had ceased to be contractile. 



