THE LARVA OF ASTERIAS VULGARIS. 123 



generally spoken of as the beginning of metamorphosis may 

 be regarded as coenogenetic precocious formation for the pur- 

 pose of shortening the metamorphosis. Examples of further 

 abbreviation of the metamorphosis are found in the case of 

 the so-called viviparous Echinoderms, where it is carried to an 

 extreme degree. 



Johns Hopkins Univeksity; 

 May 1, 1891. 



List of Papers referred to. 



(1) Agassiz, L. — 'Boston Evening Traveller,' December 22nd, 1848; also 



'Miiller's Archiv f. Anat. u. Physiol.,' 1851, pp. 122—125. 



(2) Agassiz, A. — " North American Starfishes," * Mem. of Mus. of Comp. 



Zoology,' Cambridge, Mass., 1873. 



(3) BALrouB, F. M. — ' Comparative Embryology,' vol. i. 



(4) Bkooks, W. K.—' Johns Hopkins University Circular,' No. 88, 1891. 



(5) Bury, H. — " Studies on the Embryology of Echinoderms," ' Quart. 



Journ. Micr. Sci.,' vol. xxix, 1889. 



(6) Desor, E. — " On the Development of Asterids," ' Proc. of Boston Soc. 



of Nat. History,' 1848; also 'Miiller's Archiv,' 1849, pp. 79—83. 



(7) Field, G. W.— 'Johns Hopkins Uuiversity Circular,' No. 88, 1891. 



(8) Eleischmann, a.— "Die Entwickelung des Eier von Echinocardium 



cordatum," ' Zeit. f. wiss. Zool.,' 46, 1888. 



(9) GoTTE. — " Bemerkungen zur Entges. der Echinodermen," ' Zool. 



Anz.,' 1880, pp. 324—326. 



(10) Greeff, R. — " Ueber den Bau und die Entwickelung des Asteracan- 



thion rubens vom Ei bis zur Bipinnaria und Brachiolaria," ' Sitz-ber. 

 der Markinger Naturf. Gesellsch.,' 1876. 



(11) Haeckel, E. — "Die Kometenform und die Generationswechsel der 



Echinodermen," ' Zeit. f. wiss. Zool.,' xxx, Suppl., pp. 424 — 445. 



(12) Hatschek. — " Ueber Ent. von Teredo," ' Arb. a. den Zool. Inst, der 



Univ. Wien,' 1880, Bd. iii, pp. 1—44. 



(13) Hensen, V. — "Ueber ein Brachiolaria des Kieler Hafens," 'Arch, fiir 



Naturgesch.,' 1863, pp. 242—246. 



(14) Hertwig, O. — " Beitrage zur Kenntniss der Bildung, Befruchtung, 



und Theilung des thierischen Eier," ' Morph. Jahrbuch,' i, 1875, 

 pp. 347—434. 



