LIVING BKACIIIOPODA. 383 



Fig. 4. Right half of coelomic cavity of D. lamellosa, showing oblique nerve and its termination in the posterior occlusor 

 mMcle; in this figure the retractor bracliia muscle is turned up to expose course of nerve. 



Fig. 5. Ganglion of posterior occlusor muscle, greatly enlarged, idem. 



Fig. 6. Infra-oesophageal ganglia of T. coreanica. 



Fig. 7. Portion of pallium showing gill ampullae, setae, etc., of G. pyramidata. 



Fig. 7a. Natural size of object showing region from which fig. 7 is drawn. 

 Fig. 8 to 11. Color markings of the pallium of various species of LinguUdae. The setae are purposely omitted in these 



figures except in fig. 9. 



Fig. 8. G. pyramidata. 



I'ig. 9. L. lepidula. 



Fig. 10. L. anatina: 



Fig. 11. Lingula, species unknown, from Nagasaki. 



PLATE 53. 



Details of circulation in GlottidUi pyramidata and Lingula lepidula. Arrows indicate direction of currents. 



Fig. 1 to 7. Glottidia pyramidata. 

 Fig. 1. Dorsal view showing main and lateral pallial sinuses with lacunae, and coelomic and median sinuses. 

 Fig. 2. Portion of pallium showing three rows of gill ampullae. 

 Fig. 3. A single row of gill ampullae, greatly enlarged. 



Figs. 4, 5, and 6. Transverse sections through lacune of pallium. Appearance of polygonal cells of endothelium. 

 Fig. 7. Showing regions of above sections. 



Fig. 8 to 12. Lingula lepidula. 

 Fig. 8. Dorsal view. The left brachium is shown with cirri removed. 

 Figs. 9 and 10. Opening of main pallial sinus and adjacent parts. 



Fig. 11. A portion of main pallial sinus showing diverticular lacunae; these appear quite circular in section. 

 Fig. 12. A single lacune, in section, greatly enlarged. In the drawing of Lingula, at one side, is indicated the region 

 from which tigs. 11 and 12 were taken. 



Fig. 13. Lateral sinus of G. pyramidata ; this is figured on the plate laterally. 



PLATE 54. 



Circulation, blood corpuscles and nephridia of various forms. 

 Fig. 1. Side view of G. pyramidata, showing result of injection of red fluid through peduncular cavity. 

 Fig. 2. Dorsal view of same. It will be seen that in this experiment the fluid filled the median sinus and the minute 

 vessels of the perivisceral lining, but did not enter the coelomic cavity or the sinuses of the pallium. 

 Fig. 3. Blood corpuscles of G. pyramidata. 

 Fig. 4. Same of L. lepidula. 

 Fig. 5. Same of L. anatina. 

 Fig. 6. Same of D. lamellosa. 

 Fig. 7. Same of T. coreanica. 

 Fig. 8. Same of T. septentrionalis. 

 Fig. 9. Left nephridium of G. pyramidata. 



Fig. 10. Greatly enlarged view of portion of nephrostome, idem. 

 Figs. 11, 12, and 13. Nephrostome of L. lepidula. 

 Fig. 14. Nephrostome from the under side, idem. 

 Fig. 14a. One fold of nephrostome greatly enlarged showing ciliary ridge, idem. 



