226 CEYLON PEARL OYSTER REPORT. 



LITERATURE CITED. 



(1.) 1884. Gunther, 'Zool. Collections, H.M.S. "Alert,"' 



(2.) 1889. Gunther, ' Challenger Reports,' vol. 31. 



(3.) 1893. Andrews, 'Studies Biol. Lab. Johns Hopkins University,' vol. 5, No. 4. 



(4.) 1894. Willey, 'Q. Journ. Mic. Sci.,' vol. 35. 



(5.) 1894. Kirkaldy, 'Rep. Brit, Assoc, Oxford.' 



(6.) 1895. Kirkaldy, ' Q. Journ. Mic. Sci.,' vol. 37. 



(7.) 1901. Willey, ' Q. Journ. Mic. Sci.,' vol. 44. 



(8.) 1902. Forster-Cooper. ' Fauna and Geography of Maldives and Laccadives,' 



vol. 1, Part 4. 

 (9.) 1902. Gilchrist, ' Marine Investigations in S. Africa,' vol. II. 

 (10.) 1903. Tattersall, 'Trans. Liverpool Biol. Soc.,' vol. XVII., p. 269 



EXPLANATION OF PLATE. 



Fig. 1. Caudal fin of Branchiostoma lanceolatum. All the Ceylon specimens conform more or less to this 



type. 

 Fig. 2. Head of No. IV., Table I., B. lanceolatum, to show the dark patch anterior to the dorsal fin 



and dorsal to the notochord. 

 Fig. 3. Caudal fin of B. lanceolatum, var. beldieri. Very uniform throughout the Ceylon specimens. 

 Fig. 4. Caudal fin of Asymmetron cingalense. 

 Fig. 5. Anterior end of No. X., Table III., A. cingalense, the only one in which relation of notochord 



to dorsal fin anteriorly is the same as in Kirkaldy's figure. 

 Fig. 6. The general arrangement of the anterior end of the Ceylon specimens of A. cingalense. 

 Fig. 7. Anterior end of No. XIII., Table III., A. cingalense, to show peculiar structure in the dorsal fin. 

 Fig. 8. Female A. cultelhim. 



Fig. 9. Anterior end of male A. cultelhim. Notochord not definitely clubbed. 

 Fig. 10. Caudal fin of male A. cultelhm. 

 Fig. 11. B. indicum. 



Fig. 12. Anterior end of large B. indicum. 

 Fig. 13. Caudal fin of large B. indicum. 

 Fig. 14. Anterior end of B. calij 'orniense (1). 

 Fig. 15. Posterior end of B. californiense (1). 

 Fig. 16. B. pelagicum. 



