336 A. T. MASTEKMAN. 



mesenteries. Mesomeres produced into numerous tentacles. 

 Metamere with dorsal flexure. 



(1) Phoronidea. — Loss of pre-oral lobe and notochord 

 in adult. No gill-slits. 



(2) Ceplialodiscida. — One pair of gill-slits with chordoid 



walls ; persistent notochords. 

 3. E-habdopleurida.^ 



II. Eu-chorda. 



Archimeric segmentation replaced by metameric. Single 

 dorsal notochord loses connection with the gut-wall, and dorsal 

 nervous system with the ectoderm. Protomere and mesomeres 

 reduced. Notochord extends into metamere (Urochorda, Ho- 

 lochorda), and also into protomere (Cephalochorda). 



1. Urochorda (?). 



2. Cephalochorda. 



3. Holochorda. 



References. 



1. W. Bateson. — 'Quart. Journ. Micr. Sci.,' xxiv — xxvi. 

 la. BovERi.— 'Anat. Anz.,' vii, 1892, pp. 170—181. 



lb. W. Beooks.— ' The Genus Salpa/ Baltimore, 1893, p. 303. 



2. E. H. Caldwell.—' Proc. Roy. Soc.,' xxxiv, pp. 371—383. 



3. E. H. Caldwell. — ' Quart. Journ. Micr. Sci.,' xxv, 1885. 



4. T. S. Cobbold. — ' Quart. Journ. Micr. Sci.,' vol. vi, p. 50. 



5. E. Clapakede.— ' R. und D. Archiv,' 1861, p. 537. 



6. E. Claparede. — 'Beobach. iiber Anat. und Entwick.,' Leipzig, 1863, 



p. 83. 



7. C. J. CoRi.— ' Zeitschr. f. wiss. Zool.,' xli (1890), pp. 480—568. 

 7a. M. Davidoff.— ' Mittheil. Zool. Stat. Neap./ 1889-91. 



8. F. D. Dyster. — ' Trans. Linnsean Soc. Lond.,' vol. xxii, p. 251. 



9. C. Gegenbaur.— ' Zeitsclirift,' Siebold and Kolliker, 1854, pp. 347— 



350. 



10. S. F. Harmer.— • " Challenger " Reports,' vol. xx, pp. 46—47. 



11. A. Krohn.— ' Miiller's Archiv,' 1858, pp. 293—298. 



1 For further details regarding the Archichorda see end of Part II. 



