438 



NATURE 



[March 7, 1889 



hope that I may make it interesting to you. It relates to 

 what may be called the foreign Rotifera ; that is to say, 

 to those Rotifera which have not as yet been found in 

 our islands. One would naturally like to know what pro- 

 portion tliese fo!-eign species bear to the British ; whether 

 there are any families or genera entirely absent from 

 the British fauna ; whether there appears to be any law 

 of distribution among the Rotifera ; and how far it is 

 possible to account for the existence of the same species 

 in places which are thousands of miles apart. But many 

 of the numerous memoirs, from which information on 

 I'lese points is to be derived, are only to be found, scat- 

 tered widely, in various European periodicals ; and so 

 are difficult to be procured ; while, of those that have 

 been published separately, the best are rare. 



Under these circumstances I thought it not improbable, 

 that the members of our Society might be glad to know, 

 that the task of studying and condensing these memoirs 

 liad been, in the main, accomplished ; and that 1 am 

 able now to present them with some of the results. 



In the first place, I made a list of all the known species, 

 .and marked against each the various localities in which 

 it has been found. It was curious to see, as the table 

 ;frew, how certain well-known Rotifera were picked out 

 by their rapidly advancing scores, till at last about fifty 

 typical Rotifera were separated from the rest ; while, of 

 these, a smaller group enjoyed the further distinction of 

 having a very wide range, not only in latitude and 

 longitude, but also in altitude. 



The same table showed at a glance that Great Britain 

 decidedly outstripped all other countries in the number 

 of its recorded species, having quite two-thirds of the 

 whole. Nor was this all, for the Rotifera seemed, like 

 trade, to follow the flag, and to haunt the British colonies 

 just as if they were British ships. 



The reason, for this curious pre-eminence of British 

 Rotifera, is clearly seen when we notice how those species 

 are distributed, which have as yet been found in one 

 country only. There are about 240 such species, and of 

 these no fewer than 173 (that is to say, more than two- 

 thirds) are peculiar to Great Britain. It is, of course, 

 obvious that this apparent selection of Great Britain as 

 the fathei-land of the Rotifera is simply due to the 

 greater energy, industry, and skill with which the search 

 lor new species has been pursued in this country. It is, 

 liowever, very remarkable that the naturalists of Great 

 Britain should, in late years, have added to the Rotiferous 

 fauna two and a half times as many species as the 

 naturalists of all other countries put together have done ; 

 and this highly honourable result is mainly due to 

 members of your own Society, and especially to my 

 deeply-lamented colleague and dear friend, the late Mr. 

 I'hilin Henry Gosse, F.K.S. 



After 1 had seen ho-w greatly the value of the recorded 

 distribution of the Rotifera was affected, by what I may 

 term the " personal equation," I at first feared that I 

 lihoiild obtain little else fro^n my tables than a well- 

 merited tribute to the energy of British naturalists. 

 Fuither inspection, however, showed other points that are 

 well worth your notice. 



In the first place, my lists showed that Germany, 

 •Switzerland, and Hungary come next in order to Great 

 liritain, in the total number of species that each records ; 

 and I have only to mention the names of Ehrenberg, 

 l.cydig, Cohn, Grenacher, Zacharias, Eckstein, Plate, 

 Imhof, Percy, Bartsch, Vejdovsky, Zelinka, not to say 

 many others, to make it obvious that the result is due, 

 not to the real distribution of the species in these 

 countries, but to the comparative skill and industry of 

 their naturalists. 



Next, my table shows clearly that in all cases a consider- 

 able number, and in some the great majority, of the above- 

 named fifty typical Rotifera, range throughout Britain, 

 France, North and South Germany, Denmark, Switzer- 



land, Hungary, and Russia ; so that we may reasonably 

 conclude that a considerable proportion of the 450 known 

 species would probably be found in almost any part of 

 Europe, if they were diligently searched for. Here, for 

 instance, is a list of thirty well-known Rotifera, all of 

 different genera, and all recorded in at least five of the 

 above eight European countries: — 



Floscularia ornata 

 Stephanoceros Eichornii 

 Melicerta ringens 

 Limnias ceratopbylli 

 Lacinularia socialis 

 Philodina roseola 

 Rotifer vulgaris 

 Actinurus neptunius 

 Asplanchna helvetica 

 Triarthra mystacina 

 Hydatina senla 

 Notommata aurita 

 Proales decipiens 

 Furcularia fjrficula 

 Eosphora aurita 



Diglena catellina 

 Mastigocerca carinata 

 Rattulus lunaris 

 Dinocharis pocillum 

 Scaridium longicaudum 

 Salpina miicronata 

 Euchlanis dilatata 

 Cathypna luna 

 Monostyla cornuta 

 Colurus uncinatus 

 Metopidia lepadella 

 Pterodina patina 

 Brachionus urceolaris 

 Anura^a aculeata 

 Notholca striata. 



Besides, many of the Rotifera are very tolerant of 

 climate, and appear to be able to live anywhere that they 

 can get food. For instance, Rotifer vulgaris is to be 

 found all over Europe, and at all heights ; thriving under 

 moss, near the top of the Sidelhorn, and on the Tibia, at 

 an altitude of 9000 feet above the sea. It has been met 

 with also in Nubia, on the slopes of the Altai Mountains 

 in Siberia, in Ceylon at the top of Adam's Peak, in 

 Jamaica, and in the Pampas of La Plata. Brachionus 

 pala has nearly as great a range ; for it has been found in 

 many parts of Europe, in Egypt, at the Cape of Good 

 Hope, in Siberia, Ceylon, Jamaica, and New Zealand. 

 Besides these, Diglena catellina, Hydatina scnta, Ac- 

 tinurus neptunius, and a few others, have all been met 

 with in different quarters of the globe. But the distribu- 

 tion of the Rotifera presents us with other facts quite as 

 curious as these. For not only are European species to 

 be found ranging over Asia and Africa,' but America, and 

 even Australia and New Zealand, in spite of their ocean 

 belts, possess the same familiar creatures ; and, moreover, 

 seem to have hardly any peculiar to themselves. Here,, 

 for example, is a list of Rotifera that have been found in 

 Sydney by Mr. Whitelegge, and in Queensland by Mr. 

 Gunson Thorpe : — 



Conochilus volvox 



,, bullata («. sp.) 



Asplanchna Brightwellii 

 ,, ebbesbornii 



Cephalosiphon limnias 

 Actinurus neptunius 

 Rattulus ligris 

 Notommata centrura 

 Euchlanis triquetra 

 Dinocharis pocillum 



,, triremis («, 



Brachionus militaris 

 Anuraea cochlearis 

 Pedalion mirum. 



Floscularia ornata 



,, campanulata 



,, cornuta 



Millsii 

 ,, cbronetta (&«;-.), JF 



Melicerta ringens 

 ,, conifera 

 CEciites crystallinus 



,, janus 

 Limnias ceratopbylli 



,, annulatus , ,, triremis («. sp.), W, 



,, cornuella 

 Lacinularia socialis 



,, pedunculata («. 



sp.), IV. 



Mr. Thorpe has also found what seems to be a swim- 

 ming Floscule, with a forked foot and a dorsal eye ; as 

 well as a new Noteus or Brachiojtus, with a strangely un- 

 symmetrical lorica, bearing ten spines in front, and three 

 behind. Who would ever have imagined that, in a sea- 

 girt continent, at the opposite side of the globe — in aland 

 whose fauna and flora are so strange as those of Australia 

 —we should find that twenty-four out of thirty recorded 

 species were British : and that, of the remaining six, one 

 {Floscularia Millsii) had a habitat in the United States?' 



The United States, too, Jamaica, and Ceylon all re- 

 produce the same phenomenon, though on a reduced 

 scale ; so that the quest'on at once arises. How could these 



