3-'S 



NA TURE 



[July 31, 1884 



•a paper on the microscopic structure of the coal of the Doltz 

 basin, M. Jenjourist shows that the coal contains remains of 

 Sigillarise and Lepitlopendrons, while several Russian geologists 

 are inclined to consider it as having originated only from marine 

 Algje. M. Dybovsky contributes to this volume a description of 

 a new species of fresh-water sponge from Southern Russia, which 

 is closely allied to the Dosilia baileyi of Mr. Carter, and to 

 which he gives the name of Dosilia s/eftauowii ; it is figured in 

 a plate. Finally, M. Shevyreff gives a list of Hymenoptera 

 terebrantia of the Governments of ICharkoff and Poltava ; and 

 M. Yaroshevsky publishes his fifth supplement to the list of 

 Diptera of Kharkoff. 



The last two volumes of the Memoirs of the St. Petersburg 

 Society of Naturalists (Trudy Sanctpeterbttrgskago Obschestva 

 Estestjoispytateley, vol. xiii. fasc. 2, and vol. xiv. fasc. 1) contain, 

 besides the minutes of proceedings (which unhappily do not go 

 further than March 1SS3), several valuable papers. Geology is 

 the most favoured branch. Thus we find in vol. xiii. an inter- 

 esting paper on the waterfalls of Northern Esthonia, by P. N. 

 Vemikoff. The orography of the country whose Silurian deposits 

 are cut towards the north by the abrupt terrace of the Glint, the 

 lower parts of which contain looser strata easily destroyed by the 

 water (as in the Niagara), favour the development of waterfalls, 

 the chief of which are described by the author. In the same 

 volume MM. Koudryavtseff and Sokoloff publish a geological 

 description (with a geological map) of the district of Kromy in 

 Orel. The Quaternary formations are represented by the "black 

 earth," loess, and mighty sheets of boulder-clay which cover the 

 chalk, the Jurassic clays, containing spherosiderite, and the 

 Devonian limestones, marls, and dolomites, appearing in the 

 north. The paper is accompanied with a map on a large scale. 

 In vol. xiv. we find a very interesting orographical sketch of the 

 Kola peninsula, by N. Koudryavtseff. The author has devoted 

 much attention to the leading features of this tableland, and the 

 modifications its surface has undergone under the action of the 

 ice-sheet of the Glacial period. The structure of the mountains ; 

 the parallelism of the valleys ; the glacial erosion, which has 

 covered the whole of the country with numberless depressions 

 running in the direction of the glacial striation, and producing 

 what might be called "telescopic striation"; the finer glacial 

 striae, which run north and south, or north-north-west to south- 

 south-east ; the " glacial landscape " of the country; and finally 

 its upheaval, are dealt with by the author. Several indications led 

 the author to admit that the peninsula is rapidly rising up, the 

 surest of them being the find of colonies of Balanides at a height 

 of 8 metres above the sea, and the discovery of the Buccinum un- 

 da'uni (which still inhabits the White Sea), together with broken 

 shells of Brachiopoda and Lamellibranchiata, about 280 feet 

 above the present sea-level, at Kandalaksha. N. A. Sokoloff 

 contributes to the same volume a note (with a plate) on the find 

 of teeth of Mastodon arvernensis in the Crimea, at Zamruk, which 

 would imply a wider extension of Pliocene in the yet unexplored 

 steppes of the peninsula ; and on the find, also in the Crimea, of 

 teeth of Hipparion gracile, which was so widely spread during 

 the Tertiary period from the prairies of the Missouri to the 

 Himalayas. We notice also a note by P. P. Kudiyavtseff, on 

 prehistoric man on the Oka ; and another note by M. Polyakoff 

 on the bottom-moraine at Wiborg, in Finland. 



In other branches of science we have to mention a sketch of 

 the Phanerogam flora of the Government of Minsk, by W. 

 Paszkewicz (vol. xiii.). It contains 95S species, the whole 

 number reaching probably about 1000 ; 40 of them are new for 

 this region. In vol. xiv. we find a note by M. Szihowsky on 

 the chemical constitution of different parts of the Zca Mays, and 

 two preliminary reports, botanical by A. Krasnoff, and zoo- 

 logical by A. Nikolsky, about explorations in the Altai Moun- 

 tains. The collections of 720 Phanerogams and 100 Cryptogams, 

 which have been brought in by M. Krasnoff, will surely yield 

 interesting data. As to M. Nikolsky, he gives a lively sketch of 

 the fauna of the Altai, followed by a list of observed species : 

 50 mammals, one of which, Talpa altaica, is new ; 169 birds, a 

 few reptiles and amphibia, and 16 fishes. A plate gives the 

 comparison of the T. altaica with the T. europea. 



RECENT MORPHOLOGICAL SPECULA TLONS ' 



I II. — Non-segmented Animals 



T^HERE are certain groups of animals about whose systematic 



position naturalists never seem able to remain long agreed. 



These groups are changed from place to place in our schemes 



1 Continued from p. 227. 



of classification ; and often each new discovery seems to confute 

 a current theory only to confirm that which preceded it. More 

 than any other groups, the Polyzoa, Brachiopods, and Mollusks 

 have been shifted from point to point, and it seems almost too 

 much to expect that they have even now found a permanent 

 resting-place. 



The Polyzoa were brought into connection with "Mollusks " 

 more than fifty years ago, when Milne-Edwards exhibited their 

 supposed affinities with Ascidians, and their Molluscan affinities 

 were more fully admitted when Von Siebold compared the Poly- 

 zoan lophophore and tentacles with the arms of a Brachiopod. 

 Milne-Edwards, in combining Polyzoa and Tunicates in his new 

 group Molluscoida, argued the identity of the type in every 

 detail of structure, and Huxley ("English Cyclopaedia, " 1855), 

 laying more weight than previous writers had done on the affini- 

 ties of Polyzoa with Brachiopods (as Mr. Albany Hancock was 

 perhaps the first to suggest) definitely included this last class 

 also in the group Molluscoida. The Brachiopods seemed, in 

 the light of that time's knowledge, to take a very natural posi- 

 tion among the "neural Mollusks," between the Polyzoa on the 

 one hand and the Lamellibranchs and the Pteropods'on the 

 other (Proc. Roy. Sor, 1854, p. 117). 



But in the course of the next ten years Kowalevsky's dis- 

 covery of Loxosoma seemed to supply a link between the 

 Polyzoa and Worms, and Gegenbaur, and afterwards Haeckel, 

 emphasised this relation, and finally included the Polyzoa in the 

 latter group. The Tunicata had by this time obtained, through 

 Kowalevsky's researches, an established position far removed 

 from their former allies in the " Molluscoida," and Gegenbaur 

 now analysed more critically the differences between Polyzoa 

 and Brachiopods, and (denying that either had any affinity with 

 Mollusks) maintained the eminently isolated position of Brachio- 

 pods, and asserted that their arms could no more be compared 

 with the tentacles and lophophore of Polyzoa than these could 

 with the branchial tufts of the Tubicolse. The discovery by 

 Kowalevsky ( 1 874) of the apparently segmented larva of Argiope, 

 &c. , seemed to reveal almost obscured genetic relations with the 

 Chaetopods, and at the same time Morse, working chiefly on 

 Lingula, argued elaborately that the Brachiopods are much 

 modified Annelides. Ray Lankester, on the other hand, upheld 

 the Molluscan affinities of both Polyzoa and Brachiopods, and 

 Huxley, in his "Anatomy of Invertebrates," kept the' three groups 

 in close juxtaposition. Lankester compared Rhabdopleura 

 minutely with the embryo of Pisidium (Phil. Trans. 1S74), and 

 maintained the common origin from a primitive ciliated girdle of 

 the gill-filaments of Lamellibranchs, the lophophore of Polyzoa, 

 the arms of Brachiopods, the tentacles of Phoronis, the velum 

 of embryo Mollusks and of Rotifers, and the ciliated pro- 

 boscis of Gephyrea. Huxley ("Invertebrates," p. 674), influ- 

 enced on the one hand by Lankester, and by Steenstrup and 

 Morse on the other, proposed to combine Polyzoa and Brachio- 

 pods under the name Malacoscolices, to indicate relationship 

 both with Mollusks and with Worms. Lastly, Caldwell (P. R. S. 

 18S2), by his researches on Phoronis, has thrown new light on 

 the structure of both Polyzoa and Brachiopods, and, in Lankester's 

 words ("Encycl. Brit.," Art. "Mollusca," 1SS4), " has established 

 the conclusion that the agreement of structure supposed to obtain 

 between Polyzoa and true Mollusca is delusive ; and accordingly 

 they, together with the Brachiopoda, have to be removed from 

 the Molluscan phylum." 



We may examine this last important view more closely, and 

 try afterwards to discuss -the probable ancestry of these three 

 much-debated classes. 



Actinotrocha, the larva of Phoronis, is, according to Caldwell, 

 a perfect and typical trochosphere. The larvne of Brachiopods 

 and Polyzoa are trochospheres in which, by a shortening of the 

 "dorsal " surface, mouth and anus have been approximated, and 

 the ventral surface has been enormously distended. The same 

 change takes place, and to an even greater extent, in the "meta- 

 morphosis " of Phoronis : the adult animal has both mouth and 

 anus situated at one end of a long body ; the line joining them is 

 the contracted dorsal surface ; an epistome, said to be the per- 

 sistent prse-oral lobe of the larva, lies between mouth and anus ; 

 a lophophore, whose new tentacles are adtled on either side of 

 the median dorsal line, surrounds the mouth ; within its concavity, 

 on either side of the anus, lie two ciliated pits, whose homologue 

 is found in Rhabdopleura. A single pair of nephridia exist. The 

 body-cavity is traversed by mesenteries, one of which is ventral, 

 and attaches the outside of both descending and ascending limbs 

 of the alimentary canal to the body-wall ; two are lateral, and 

 pass from the side of the stomach to the body-wall, dividing the 



