596 



COMPARATIVE ANATOMY 



CHAP. 



A. F. Marion. Audes zoologiques sur deux espices d' EnUropneustes. Arch. Zool. 



ginir. et expir. (2). Tome IV. 1886. 

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



Ueher Toraaria. Zeitschr. f. wiss. Zool. 20 Bd. 1870. 

 T.H.Morgan. Orowtli and inetamorphosis of Tornaria. Journ. Morpli. V. 1892. 



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



Joh. Miiller. Vchcr die Lariien und die Metainorphose der Echinodermen. Part 2. 



Akad. d. Wissenseh. 1848. Berlin, 1850. 

 Wladimir Schimkewitsoh. The Fauna of the Uliitc Sea: Balanoglossus Meresch- 



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

 J. W. Spengel. Die Enteropneusten. Fauna and Flora des Golfes mn JVeapel. 



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

 W. F. R. Weldou. Preliminary note on a Balanoglossus larva froin the Bahamas. 



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

 R. V. Willemoes-Suhm. Biologischc Beohachtungen iiher niedere Meercsthicre. 4. 



Ueher Balanoglossus Kupfferi aus dem Oeresund. Zeitschr. f. wissenseh. Zool. 



21 Bd. 1871. 

 A. Willey. A'inphioxus 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 

 fiat, 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- 



PiG. 469.— Cephalodiseus doaecaiophus, from the hind the anterior end of 



ventral side (after M'lutosh). 1, Tentacles; 2, buccal fV,„ ventral sidp thp mnnth 

 shield=proboscis:8,mouth;4,buds;6,pedicle;6, trunk. "^^^ -ventral Side, tne mOUtft, 



and between the two the 

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



