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EXPLANATION OF THE PLATES. 

 Plate XV. 



Fiy, 1 A, B, C, D, and E represent the genital markings and orifices 

 of D. somavca'patana, D. scandeits, D. elegans, D. niodcsta, 

 and D. paradoxa, respectively. 



Fig. 2 A, B, C, 1), and E are the spermathecal apparatus of the species 

 in the same order as in fig. 1. Tlie atrial pouch in fig. D is 

 contained in the septal wall 7/8. The pouches are cleared in 

 acetic acid, so as to show the nature of the internal cavity. 



Fi(j. 3 a, b, e represent the dissections of D. sontavarpatana, D. 

 scandeus, and D. paradoxa. The septal deflections in the 

 genital somites are a marked feature. 



Plate XVI. 



Fig. 4. The left half of two somites' length of alimentary canal of young 

 Z). paradoxa. The anterior division shows the development 

 of an enteric appendage and the second half contains a fully- 

 developed appendage. A few of the multiplying cells have 

 migrated to the tips of the muscle-fibres. The reflected 

 membrane on the base of the appendage in the second half of 

 the figure is the outer connective-tissue wall of the doisai 

 vessel. 



Fig. 5. An entire nephridium of D. paradoxa : at points a, h, and c the 

 structure of the vesicle and the different lobes is indicated in 

 optical section. 



Fig. 5 a. An entire nephrostome of D. somavarpatana, examined in 

 glycerine. The secondary funnel is pi'ovided with stiff cilia. 



Fig. 6. Transverse section of the nerve-cord of D. somaoarpatana. 



Fig. Ga. A length of one-half of the nerve-cord of the same species, 

 washed in silver nitrate and stained in methylin-blue, 

 illustrating the mode of dendritic connections. Each nerve 

 is composed of 8 to 10 fibres, of which only two are shown in 

 the figure. The relative positions of the different nerve-cells 

 and their dendritic connections have been drawn through 

 Spencer Lens camera lucida. x 76. 



