MR. J. D. MACDONALD ON THE ANATOMY OF EURYBIA GAUDICHAUDI. 249 



EXPLANATION OF THE PLATE. 

 Tab. XLIII. 



Fig. 1. Eurybia Gdndichaudl. Natural size. 



Fig. 2. Eurybia Gaudichaudi, magnified to show more distinctly its head, tentacula, oral aperture armed 

 with lateral dental cells, the swimming-fins, and foot. The abdominal viscera are imperfectly 

 seen through the transparent mantle. 



Fig. ;?. Portion of the fibro-cartilaginous mantle, highly magnified. 



Fig. 4. The lateral labial teeth, forming in this case a double series. 



Fig. 5. Six of the dental cells belonging to the right side, still further m.ognified to show the longitudinal 

 cutting edge near the external border of each. 



Fig. 6. Three transverse rows of the lingual ribbon. In this view the curvature of the lateral teeth is 

 scarcel}' apparent. 



Fig. 7- The auditory capsule containing otokonial particles. 



Fig. 8. Generative systems: a a. expansion of the lobules of testis and ovarium lying in juxtaposition; 

 A h. ova seen through the walls of the ovarian lobuli ; a c. primary oviducts uniting in a d, 

 the common duct; a e. vesicula seminalis; a /'. the vas deferens; b a. pointed extremity of 

 the penis, composed of indurated cells, and traversed by the ejaculatory canal : b b. sperma- 

 tozoa exhibiting their peculiar looping and twisting movements. 



Fig. 9. Embryo of Eurybia within the ovum : a. frontal and lateral ciliated head-lobes ; b, b. subceso- 

 phageal ganglia supporting the auditory sacs with their single primordial otolithes ; c. alimentary 

 canal with the rudimentary abdominal viscera ; d d, d d. two ciliated rings which gird the exte- 

 rior of the incipient cartilaginous mantle. 



Fig. 10. Structural elements of the mantle: a. portion of one of the ciliated rings of the embryo; 

 b. stages of development of the fibrous tissue ; c. cartilage-cells in different stages. 



