596 



COMPARATIVE ANATOMY 



CHAP. 



A. F. Marion. Etudes zoologiques sur deux especcs d" Entfropncustcs. Arch. Zool. 



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

 E. Metschnikoff. Untersuchungen uber die Metamorphose einigcr 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. Mliller. Ueber die Larven und die Metamorphose der Echinodermcn. Part 2. 



AJcad. 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 Enteropneustcn. Fauna and Flora t/rs Golfcs von Neapel. 



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

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



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

 R. v. Willemoes-Suhm. Biologische Beobachtungen uber nicdere Meercsthierc. 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 



FIQ. 49. Cephalodiseus dodecaiophus, from the 



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 

 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- 

 hind the anterior end of 



and between the two the 

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



