596 COMPARATIVE ANATOMY chap. 



A. F. Marion. Etudes zoologiques sur deux csptccs d'Hnt^rojmcustcs. Arch. Zaol. 



gc'ner. ct cxpir. (2). Tome IV. 1886. 

 E. Metschnikoff. Untersuchungen ilber die Metamorphose ciniger Secthiere. 1. 



Uchcr Turnaria. Zcitschr. f. wiss. Zool. 20 Bd. 1870. 

 T. H. Morgan. Grov:th and vietaviorphosis of Tornaria. Journ. 3£or2)h. V. 1892. 



Til c Development of Balanoglossus. Journ. Morph. Vol. IX. 1894. 



Joh. Miiller. JJelcr die Larvcn und die Metamorphose der Echinodermen. Part 2. 



Akad. d. JFissensch. 1848. Berlin, 1850. 

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



Jcorsl-ii Jl'agiicr. St. Petersburg, 1889. (In Russian.) 

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



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

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



Proceed. Boy. Soc. London. Vol. XLII. 1887. 

 R. V. Willemoes-Suhm. Biologische Beohachtimgen iiber niedere Meeresthierc. 4. 



Ueber Balanoglossus Kupfferi ems dem Oeresund. Zcitschr. f. toissensch. Zool. 



21 Bd. 1871. 

 A. Willey. Amphioxus cmd 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 

 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 tiie hind the anterior end of 



ventral side (after M'Intosh). 1, Tentacles ; 2, buccal ^J^g ventral side, the mOUth, 

 shield = proboscis; 3, luuuth; 4, l)uds; 5, pedicle; 0, trunk. i i , j_i j_ ii_ 



and between the two the 

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



