596 



COMPARATIVE ANATOMY 



CHAP. 



A. F. Marion. ^Etudes zoologiques sur deux especes d 1 Elite" ropncustcs. Arch. Zool. 



gtner. et exper. (2). Tome IV. 1886. 

 E. Metschnikoff. Untersuchungen ilber die Metamorphose einiger Seethiere. 1. 



Ueber Tornaria. Zeitschr. f. wiss. Zool. 20 Bd. 1870. 

 T.H.Morgan. Growth and metamorphosis of Tornaria. Journ. Morph. V. 1892. 



The Development of Balanoglossus. Journ. Morph. Vol. IX. 1894. 



Job. Miiller. Ueber die Larven und die Metamorphose der Echinodermen. Part 2. 



Akad. d. Wissensch. 1848. Berlin, 1850. 

 Wladimir Schimkewitsch. The Fauna of the White Sea : Balanoglossus Meresch- 



kovskii Wagner. St. Petersburg, 1889. (In Russian. ) 

 J. W. Spengel. Die Enteropneusten. Fauna and Flora des Golfes von Neapel. 



18 Monographic. Berlin, 1893. The most important recent work. 

 W. F. R. Weldon. Preliminary note on a Balanoglossus larva from the Bahamas. 



Proceed. Roy. Soc. London. Vol. XLII. 1887. 

 R. v. Willemoes-Suhm. Biologische Beobachtungen uber niedere Meeresthiere. 4. 



Ueber Balanoglossus Kupfferi aus dem Oeresund. Zeitschr. f. wissensch. Zool. 



21 Bd. 1871. 

 A. Willey. Amphioxus and the ancestry of the Vertebrates. 1894. 



Appendage to the Enteropneusta. 



Cephalodiseus and Rhabdopleura. 

 I. Cephalodiseus (Figs. 469-471). 



The body is about 1 mm. long, almost bean-shaped, bilaterally 



symmetrical; it is rounded 

 posteriorly and anteriorly 

 flat, with a slight backward 

 slope. The most important 

 organs which can be distin- 

 guished externally are found 

 in this anterior sloping sur- 

 face, while in the whole of 

 2 the rest of the body only 

 one organ appears, viz. a 

 cylindrical stalk or pedicle, 

 which rises from the ventral 

 side of the rounded posterior 

 end of the body. 



In that part of the body 

 which projects most anteri- 

 orly, i.e. the anterior end 

 of the dorsal side, lies the 



anus, while somewhat be- 



FIG. 469. Cephalodiseus dodecaiophus, from the hind the anterior end of 



ventral side (after M'IntOSh). 1, Tentacles; 2, buccal 4-},^ vpr ,t ra l ~\A~ 4->, p nirmtfc 

 shield = proboscis ; 3, mouth ; 4, buds ; 5, pedicle ; 6, trunk tn V6ntral Slde > tne mOUth, 



and between the two the 

 slope mentioned above, the inter -stomatal region. The median 



