14 Mr. F. E. Beddard on the 



The only autlior who has seen, described, and figured the 

 developing embryo of jEolosoma is Maggi *. " The t°:^y^ 

 he remarks [ihid. p. 15), " up to the complete formation of the 

 embryo is always covered by a very resistant membrane, 

 which may be compared to an egg-shell." The ovum when 

 deposited has no longer a spherical form, but is oblong, formed 

 of an outer membrane (the "egg-shell"), with an inner 

 vitelline membrane, which surrounds the granular contents. 

 As the embryo develops out of the ovum the red oil-globules 

 appear, and at a comparatively early stage. The embryo 

 can and does move freely about in tlie cavity of the shell. 

 When hatched the setje are only just visible. The figures 

 illustrating this description (tav. ii. fig. 11, A-f) show a 

 progressive increase in size of the whole ovum, which is, when 

 fully mature, very minute. The drawing of the embryo just 

 before hatching measures a little more than 1 inch in length, 

 and is magnified 700 times. 



Maggi speaks of the whole structure as an q^^. Yej- 

 dovsky t, however, says " Nach Maggi sind die abgesetzten 

 CoconsxonyEoIosoma elliptisch, durchsichtig,und die Erabryo- 

 nalentwicklung, &c." He regards them as cocoons, and the 

 resistant membrane figured and described by Maggi as the 

 chitinous wall of the cocoon. It is rather surprising that 

 Maggi did not arrive at the same conclusion, since he correctly 

 described the clitellum, which is known to be the organ con- 

 cerned with the formation of the cocoon. Possibly, however, 

 the difference in shape which the supposed cocoon of jsEoIo- 

 soma exhibits as compared with those of other Oligochreta, 

 led IMaggi to the view that the membrane in question does 

 iiot represent a cocoon. In all Oligocha^ta, so far as is known 

 at present without a single exception, the cocoon, which 

 varies in form, is invariably prolonged at either end into a 

 longer or shorter process, particularly long in Criodrilus. 

 Otherwise the cysts of ^olosoma might well be supposed to 

 be cocoons, even though they contain, according to Maggi, 

 but a single embryo ; for the Enchytrajidaj and ^aidomorpha, 

 the nearest allies of jEolosojua, dej)osit only one ovum in each 

 capsule. This fact was first discovered by the industrious 

 investigator Jules d'Udekem |, and afterwards confirmed by 



Vejdovsky § and ^tolc ||. In the figure of the cocoon of 



* Unless there is any statement made in Stoic's paper. 

 t ' System und Morph. d. Oligochaeten,' p. 10. 



J " Aouvello Clas^ihcation des Aunt'^lides s^tigeres abrancbes," RiiU. 

 Acad. Roy. Jielg. t. xxii. 



§ ' Monogrnpliio d. Enchytiaeideu.' 



II "rii.^pevky kii StudiuXaidonunpli.." SR. Rohni. Ge.<!. 1837. 



