A Coiitribut. of the Embryol., Li fe-hi story, a,ucl Classificiit. of the Dicyemids. 83 



49. Wagener, G. »Über Gyrodactylus elegans von Nordmann. « 'Areh. f. Anat. 



u. Physiol.', p. 768, 1860. 



50. Weismann. »Die Entsteh, d. Eizellen in d. Gattung Eudendrium.« 'Zool. 



Anz.', IV, p. Ili, 1881. Comp, earlier papers in 'Zool. Anz.' 1880, p. 226 

 and 367. 



51. Whitman. »Embryology of Clepsine.« 'Quart. Journ. Mie. Sci.', 1878. 



52. Vigeliiis. »Über das Excretionssysteni d. Cephalopoden.« 'Nicderl. Arch. f. 



Zool.' V, 1880. 



Explanation of Plates 1 — 5. 



(residual 



Figs. 1 — 15 [Dicyema moschatum] magnified 465 diam., except fig. 14 which is 



magnified 280 diam. 



Fig. 1. Anterior portion of a primary Nematogen, 0.S5mm in length, seeu from 

 one side. In front of the central nucleus [ne] of the axial cell are a fuUy 

 formed embryo (0.1 mm long) containing a central nucleus and two primary 

 germ-cells [pg], and scattered vermific germ-cells [luj]. Besides what is 

 Seen in the figure, this Nematogen contained in the posterior portion only 

 a few germ-cells and a few early stages of vermiform embryos. Ace ti c 

 acid. 



Fig. 2. Portion of a Rhombogen (1.2 mm long) seen from ventral side. This 

 Rhombogen contained one Infusorigen and various stages of infusoriform 

 embryos, and two large nuclei, seen in the fig. One of these nuclei is the 

 »central nucleus« of the axial cell, the other is a paranucleus. They are 

 so nearly alike that it is impossible to say which is the central nucleus 

 and which the paranucleus. Acetic acid. 



Fig. 3. A helmet-shaped calotte of a Rhombogen (1.2mm long), seen from the 

 right side. This individuai contained the same Clements in its axial cell 

 as fig. 2. The two round nuclei were lodged in the anterior end of the 

 axial cell, as seen in fig. 13. Acetic acid. 



Fig. 4. A calotte of a Rhombogen (3.40mm long), seen from the left side. The 

 ventral polar cells are here, as in most of these figures, larger than the 

 dorsal cells. Contained many embryos and several free nuclei. 

 Acetic Acid. 



Fig. 5. A very oblique calotte of a Rhombogen (3.50mm long), seen from the 

 right side. Acetic acid. 



6* 



