ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 387 



lu the second half of this memoir, the more general questions and 

 conclusions to which a study of some of the described organs lead, are 

 discussed in great detail ; one of the most interesting of these is the 

 phylogeny of the nephridial system ; here we have only space to say 

 that this question is considered under the heads of the significance of the 

 ectodermal terminal portion of the unpaired efferent ducts of the thoracic 

 nephridia, the origin of the variations in the form of these organs, and 

 the genital tubes. 



In conclusion the author discusses the affinities of the Hermellidaa 

 and Serpulidse, and his views are given in the adjoining tabular form. 



Abnormal Earthworm.* — Mr. E. Broom reports on another earth- 

 worm with bifid hinder ends, several of which have been noticed during 

 the last few years. Eeminding us of Kleinenberg's discovery that, in 

 Lumbricus trapezoides, two complete individuals are normally developed 

 from one ovum, he suggests that this sometimes happens in L. terrestris ; 

 in support of this view he states that the two posterior parts of the 

 worm examined by him are attached by their sides, the ventral surface 

 of each part being continuous with that of the front part of the body. 

 Although in some of the already published cases the posterior ends 

 were unequal, Mr. Broom thinks it probable that they were equal at an 

 early stage, but for some reason or other developed unequally, as is 

 known to be frequently the case with double monsters of the higher 

 animals ; these last may, indeed, owe their origin to a change in the 

 ovum similar to that which normally happens in L. trapezoides. 



Development of Coelom in Enchytroeides Marioni-t — M. L. Eoule 

 has studied the development of the coelom in this marine OligochaBte. 

 He finds that it appears in the form of irregular cavities hollowed out in 

 the mass of mesoendoblastic cells ; some of these cells become free in 

 the coelomic cavities, and have a complete resemblance to the typical 

 mesenchymatous elements. As the coelom of Polygordius is formed on 

 the epithelial plan, it follows that the mode of appearance of the meso- 

 blast and of the coelom is only of secondary importance, and the 

 Hertwigs' division of the Metazoa into Enterocoelia and Pseudocoelia 

 cannot be considered natural. 



Structure of Clitellio.J — Mr. F. E. Beddard is able to make some 

 additions to Claparede's account of the anatomy of this oligoch^te. 

 Like many other writers, he confounded the testes with the vesiculsB 

 seminales, and did not describe the true testes at all. They lie in the 

 tenth segment, and each organ is long and narrow. The presence of 

 oviducts is recorded, and as Stole has already seen them in Ilyodrilus 

 and Psammoryctes, it is probable that they will be found to be invariably 

 present in the Tubificidae. As in that group generally, the mature ova 

 of ClitelUo are of very large size (half the diameter of the body), and 

 are loaded with yolk-spherules ; they are inclosed in independent ovisacs. 

 The author points out the more important differences between ClitelUo 

 arenarius and C. ater, and shows that the two are not congeneric ; the 

 latter will be better placed in Eisen's genus Hemituhifex. Mr. Beddard 

 takes the opportunity of making a few remarks on some other marine 

 species of Tubificidge. 



* Trans. Nat, Hist. Soc. Glasgow, 1889, pp. 203-6. 



t Bull. Soc. d'Hist. Nat. Toulouse, xxii. (1888) pp. Iviii. and lix. 



X Proc. Zool. Soc. Lond., 1888 (1889) pp. 485-94 (1 pi.). 



