74 



nature: 



[November 28, 1895 



EARTH-WORMS AND STREAM-WORMS. 

 A Monograph of the Order oj Oltgochata. By F. E. 

 Beddard, M.A., F.R.S. Pp. 769, 5 plates, and wood- 

 cuts. (Oxford : Clarendon Press, 1895.) 

 IT seems, at first sight, somewhat curious that such 

 common animals as earthworms, occurring as they 

 do all over the globe, should have received so little 

 attention from zoologists until recent years : yet the 

 neglect is not really to be wondered at, for earthworms 

 are very much alike, and are only distinguishable from 

 one another with difficulty even by a zoologist, while to 

 the non-scientific traveller, collector or settler — to whom 

 students of other classes of animals owe so great a debt 

 — earthworms present no attractive character of form, 

 ^nd rarely of colour. Their subterranean habits, too, 

 protect even brilliantly coloured, or specially large, species 

 from the keen eye of the collector. Some of these worms 

 reach a length of four feet, others are less than an inch ; 

 whilst most are uninterestingly coloured, there are some 

 bright ones. Megascolex cceruletis is a beautiful peacock 

 blue, Microchceta rappi is olive green, and pink below. 



Notwithstanding their general unattractiveness, it 

 might have been expected, however, that professional 

 zoologists would have been acquainted with the anatomy 

 of foreign earthworms long before the Franco- Prussian 

 war ; yet the first description of the internal organisation 

 of a worm, recognised as being different from our 

 European earthworms, only dates from 1868. About the 

 time of this war, M. Perrier was preparing an account of 

 the anatomy of nine new genera from various parts of the 

 world, which were in the museum at Paris. After the 

 publication of this memoir, in 1872, we have a gap of 

 more than ten years, ere the number of foreign genera 

 was increased ; then, in 1883, Mr. Beddard described 

 Typhccus from India. But from 1880 onwards, a con- 

 stantly increasing number of contributions to the anatomy 

 of the group has been published, so that, while in 1884 

 the bibliography in Prof Vejdovsky's valuable mono- 

 graph contains 283 references, that just published by 

 Mr. Beddard refers to more than 650 memoirs. 



In the handsome monograph under notice, Mr. 

 Beddard treats his subject in a different manner from 

 that followed by the Bohemian naturalist, who, to a very 

 great extent, confined himself to those species which had 

 come under his own observation. The present author, 

 however, while bringing together facts collected by him- 

 self during the past fifteen years, deals fully with the 

 researches of other zoologists. Vejdovsky paid more 

 special attention to the aquatic forms ; Beddard gives an 

 adequate account of the entire group of Oligochteta. 

 His work opens with a clear and excellent account of the 

 general anatomy of tha group, an account not over- 

 burdened with unnecessary detail, but yet containing 

 discussions on many important points of morphology. 

 This chapter should be of the greatest value to the 

 general zoologist, who has long been in need of such an 

 authoritative summary ; for the group usually receives 

 but scant attention from him, as after a detailed account 

 of the anatomy and development of the British earth- 

 worm (to wn:ch, by-the-by, he frequently gives a wrong 

 name), he leaves the rest of the earthworms as if they 

 were not. Yet at least seventy-five genera of earth- 

 NO. I 36 I, VOL. 53] 



worms are known, some of which contain 100 species ; 

 and even in Britain we have as many as sixteen species^ 

 belonging to four genera. 



In this anatomical chapter the author gives a very 

 detailed and comparative account of the structure 

 usually known as " prostate " or " atrium," which is 

 generally connected with the end of the sperm duct ; he 

 suggests the term "spermiducal gland," which is in every 

 way a useful and distinctive name. These structures 

 have already received discussion at the hands of himself 

 and others, and in the present book he essentially agrees 

 with a view put forward by myself some time ago, though 

 he misunderstands my views as to the Eudrilidae. He is 

 wrong in his statement that there is no peritoneum sur- 

 rounding the " cement gland " of Tulificids, for I have 

 figured this in the case of Heterochceta. He adopts the 

 view, in which I quite agree, that the spermiducal glands 

 have been derived from structures, such as occur in 

 Microchceta and Kynotiis, entirely independent of the 

 sperm duct, with which they have, in most cases, become 

 secondarily connected. 



The monograph, unlike Vejdovsky's, gives a diagnosis 

 of every known species of Oligochceta, both aquatic and 

 terrestrial, which has been described in sufficiently 

 recognisable terms ; consequently, the book is invaluable 

 to the speciahst and to museum curators. The only 

 member of the class which we miss is that peculiar leech- 

 like parasite on the gills of crayfish, Brattchiobdella. 

 This has long been recognised as an Oligochaete, and it is 

 not clear why Mr. Beddard has omitted it. 



The chapter dealing with the classification and 

 phylogeny of the group contains much that is of interest, 

 and is by no means the " dry bones " that a systematic 

 work frequently is. The class is divided into three 

 "groups" of equal value (i) : the Aphanoneura, for the 

 genus jEolosovia; (2) the Microdrili, or aquatic worms and 

 Moniligastridae ; (3) the Megadrili, or earthworms. Each 

 of the latter " groups " (to which he does not give a 

 technical term) he divides into families, some of which 

 are grouped to form " superfamilies." But I cannot alto- 

 gether agree with him in this primary subdivision. It is 

 true that in 1890 {Quart. Jour. Micr. Sci.) I suggested the 

 terms, Megadrili and Microdrili, much in the same sense 

 as he uses them ; but more recently 1 have been led to 

 adopt Vejdovsky's opinion, viz. that all earthworms (except 

 Moniligaster) form one family, and are to be contrasted 

 with each (not all) of the families of water-worms. 

 Beddard endeavours (on pp. 158 and 171), rather 

 laboriously, it seems to me, to define these two " groups," 

 but the MoniligastridcC have always been a stumbling- 

 block, and Prof A. G. Bourne's recent memoir {Quart, 

 Jour. Micr. Sci. xxxvi.) tends to emphasise rather than to 

 diminish the difficulty ; for the clitellum oi Moniligaster, 

 on which Beddard lays much stress, is there described as 

 being quite like that of an earthworm, and not like that 

 of a water-worm. 



Mr. Beddard's careful analysis of the affinities of the 

 various families to one another, and, in later chapters, of 

 the intei -relations of the genera, is a distinctive feature of 

 this monograph, and he calls to his aid the facts from 

 geographical distribution to support his contention that 

 the Perichaetida,^ are the most archaic earthworms. The 

 primitive arrangement of the bristles in earthworms was, 



