THE LARVA OF ASTEEIAS VULGARIS. 125 



(33) Selenka.— " Zoologiscbe Studien : — I. Befruchtungen des Eier von 



Toxopneustes variegatus," ' Ein Beitrag zur Lehre von der 

 Befruclitung und Eifurchung/ Leipzig, 1878. 



(34) Selenka,—" Keimblatter der Echinodermen," ' Stud. ii. Ent. d. 



Tiiieren,' Wiesbaden, 1883. 



(35) Saeasin, p. and E. — " Ueber die Anal, der Ecbinotburiden und die 



Phylogenie der Ecbinodermeu," ' Ergebn. naturw. Forscb. auf Ceylon, 

 1884-6,' Bd. i, Wiesbaden, 1888; abstract in 'Journ. Roy. Micr. 

 Soc.,' London, 1885, pi. vi, pp. 956—958. 



(36) Semon, R. — "Die Entwickelung der Synapta digitata, und die 



Stammesgescbichte der Ecbinodermen," 'Jenaische Zeitschrift fiir 

 Naturwissenscbaft,' xxii, New Series 15, 1888. 



(37) Semon, E,. — "Die Holologien innerbalb des Ecbinodermenstammes," 



' Morpb. Jabrbucb,' xv, 1889. 



(38) Semon, R. — "Zur Morphologic der bilateralen Wimperscbuure der 



Ecbinodermen-Larven," ' Zeit. f. wiss. Zool.,' N. E., Bd. xviii, part 1, 

 1890. 



(39) VoGT, C, AND Young, E. — ' Lebrbucb der prak. vergl. Anatomic, 



Ecbinodermen,' 9 — 11 Lieferungen, 1886-7, Braunscbweig. 



EXPLANATION OF PLATES XIII, XIV, & XV, 



Illustrating Mr. George W. Field^s paper on " The Larva of 

 Asterias vulgaris.'* 



List of Reference Letters. 



a. Anterior. ««. Anus, ap. Apical plate, ar. Arcbenteron. a. o. b. 

 Adoral ciliated band. h. c. Branched cells, hi. Blastopore, c. t. Connective 

 tissue, c. 0. b. Circumoral ciliated band. d. Dorsal. E'^. Median anal- 

 paired arm. E-. Dorsal anal-paired arm. E^. Ventral anal-paired arm. 

 E^. Dorsal oral-paired arm. E^. Ventral oral-paired arm. E^. Unpaired 

 anterior arm. Ec. Ectoderm. El. Enterocoel. ge. Germinal epithelium. 

 int. Intestine, m. Muscle. mes. Mesencbyme. m. m. Mesencbymatous 

 muscle-fibres, mo. Moutb. n. Nucleus. 0. Ovum, o, d. Oral depression. 

 w. (Esophagus, p. Posterior, p. b. Polar bodies, p. c. Pore canal, pe. 

 Peritoneum, p. I. Preoral lobe. p. v. a. Preorai ventral area. sh. Stomach. 



