386 EDWARD S. :\rOKSE ox LIVIN(; r.liACIIIOPODA. 



Fig. 10. So-called heart. 



Fig. 11. Another view of same organ slii;htly coiiipresseil. 



Fi"s. 12 and 13. Different views of genital gland. 



I'LATK i;o. 



External gland.s of Trn-bi-dtuUna septentrloindis. 



Fig. 1. Shells thrown wiih/ly apart rnptnring anterior coelninic wall, .showuig braehia, position of nephriclia and relation 

 of external glands to nephiidial openini^s. 



Fig. 2. Another view of nephridia with external glands. 



Fig. 3. External gland compressed with glandular particles forced out. 



Fig. 4. Greatly enlarged view of lobule of external gland showing ciliated ei>ithelinin. 



Fig. 5. External gland showing spiculae on .surface. 



Fig. G. Nephridia with external glands surrounditig their terminations. 



Fig. 7. Greatly eidarged view of right nephridial tube with external glaiul. 



Fig. 8. Tubular portion of nephridia ensheathed by external gland. 



Fig. i). Another view of nephridium .surroundeil liy lobules of external gland. 



Figs. 10 and 11. External glands. 



Fig. 12. Ventral view of anterior wall of coelomic cavity showing promiueiu character of external glands with azygos 

 process between. 



Fig. 13. L(nigitudinal section of T. septentriomilin, showing position of external glands projecting iiuo pallial cavity. 



PLATE fil. 

 Early stages of various forms. 



Fig. 1. Lingula, species unknown, from N:igasaki. 



Figs. 2, 3, and 4. Discinisca steltii. 



Fig. 5 to 12. I), lamellosa. 



Fig. 13 to It). Various stages of T. aeptentrioniUis, reproduced from the author's memoir on early stages of this species. 



Fig. 17. Ilemithyris psittacen. The natural size is indicated by the small outline. 



Printed, July, 1!)02. 



