TH 15 DEVELOPMENT OF THE- CAPE CEPHALODISCUS. 209' 
References. 
1. Andersson, K. A. — “ Eine Wiederentdeckung von Cephalo- 
discus,” ‘Zool. Anz.,’ xxvi, 1903, p. 368. 
2. “ Die Pterobranchier der schwedischen Siidpolar-expedi- 
tion, 1901-1903,” * Wise. Ergebn. schwed. Siidpolar-Exped.’ v, 
1907. 
3. Braem, E. — “Pterobranchier mid Bryozoen,” ‘Zool. Anz.’ xxxviii, 
1911, p. 546. 
4. Gilchrist, J. D. F. — “Observations on the Cape Cephalodiscus 
and some of its Early Stages,” with an Appendix by Sidney F. 
Harmer, ‘Ann. Mag. Nat. Hist.,’ ser. 8, vol. xvi, 1915, p. 233. 
5. Harmer, S. F. — “ The Pterobranchia of the ‘ Siboga ’ Expedition,. 
with an Account of other Species,” ‘ Resultats des Explorations 
a bord du “ Siboga,” Monogr.’ xxvi bis, 1905. 
6. Masterman, A. T. — “ On the further Anatomy and the Budding 
Processes of Cephalodiscus dodecalophus,” ‘Trans. Roy. 
Soc. Edinb.,’ xxxiv, 1900, p. 507. 
7. Ridewood, W. G.— “A new species of Cephalodiscus (C. 
gilcliristi) from the Cape Seas,” ‘Mar. Inv. S. Africa,^ 
vol. iv, 1908. 
8. Schepotieff, A. — “Die Pterobranchier des Indischen Ozeans,” ‘Zool. 
Jalirb. Abt. Syst.,’ xxviii, 1909, p. 429. 
EXPLANATION OF PLATES 13 and 14, 
Illustrating Dr. J. D. F. Gilchrist's paper “On the Develop- 
ment of the Cape Cephalodiscus (C. gilchristi, 
Ridewood)." 
Explanation of Figures. 
The following reference letters are used in the figures : an. Anus. 
arch. Archenteron. b. m. Basement membrane. d. Yolk detritus. 
end. Endoderm. ex. y. c. External yolk columns, i. y. c. Internal yolk 
columns, inv. s. o. Involution in nervous tissue of sense organ. N.. 
Nucleus, n. Nucleolus, p. inv. Posterior invagination. p. v. inv. 
Postero-ventral involution, p. v. th. Postero-ventral thickening, s. o. 
Sense organ, vit. Vitellophag. v. th. Ventral thickening, y. Yolk. 
y.gr. Yolk granules, y.l. Yolk lumen, y.n. Yolk nucleus. 
[All the figures have been drawn by camera lucida except figs. 5. 
