MUSEUM OF COMPARATIVE ZOOLOGY. 43 



REFERENCES TO PLATES. 



Plate I. 



Fig. 1. Diagram of Terebratula vitrea, natural size. 



2. Diagram of Terebratula cubensis, natural size. 



3. Diagram of Waldheimia floridana, natural size. 



4. Diagram of Waldheimia septigera, natural size. 



5. Diagram of Cistella lutea, much enlarged, showing the loop, septum, 

 and disk-like muscular attachments. 



5 a. Side view or section of the same, showing the ribbed septum. 



6. Diagram of Cistella rubrolincta, much enlarged, showing the interior 

 and the transverse plate of the septum. 



6 a. Side view of the same. 



7 a, b. Crania (? anomala var.) Pourtalesii, inside and outside of the 

 upper valve much enlarged. 



8. Fry of Terebratula cubensis, very much magnified : a, nucleus of the 

 neural valve with its two pores (b) ; c, constricted neck of the valve beyond 

 the nucleus ; d, thin septum closing the upper part of the foramen ; /, fora- 

 men; h, nucleus of the hsemal valve with pores. 



It will be observed that, in the closed apical termination, the posterior 

 lamina partly closing the foramen, and the lateral grooves or areas on earh 

 side of the latter, this immature form presents characters entirely analogous 

 to those (upon which Professor King has lately based a genus, Agulhasia,) 

 exhibited by a species which I am inclined to regard as an immature Tere- 

 bratulina. 



9. Soft parts of the same : a, horseshoe-shaped membrane ; b,f, muscles ; 

 c, mouth and bag-shaped stomach, with (d) hepatic lobules. 



10. Spicule from adult Terebratula cubensis, much magnified. 



11. Coecal termination of the intestine of the same, enlarged. 



12. Oyaria of Terebratula cubensis, enlarged, showing the position with 

 relation to the muscles of the neural valve. 



13. Same, in the hamial valve. 



14. Diagram of the parts about the mouth from the side, enlarged : A, 

 nasiform body ; B, intercorporeal groove ; C, supra-cesophageal body ; D, 

 excavation below it and behind the brachia ; E, brachia ; F, mouth ; H, 

 dorsal adjustor muscles (retractors of Owen) ; I, hepatic lobules ; J, heart 

 with vessel ; K, side of stomach and intestine, from which the hepatic 

 lobules have been removed, showing the two ducts, by which the lobules 

 communicate with the cavity of the stomach. 



15. Diagram of the supra-cesophageal portion of the body from in front, 



