390 EMBRYOLOGY 



in structure to those of Amphioxus ; but a detailed comparison reveals 

 in them organs of different phylogenetic origin (Spenc.el). The coelom 

 of the Enteropneusta exhibits other conditions than in the Chordata. 

 The probability of the relationship of Balaiioglossus to the Echinodenns>, 

 on the contrary, has, it may be said, been increased by recent investiga- 

 tions. A comparison of Tornaria with the larvs of Echinoderms, so far 

 as regards the external form, and imrticularly the structure, is perhaps 

 still possible. The apical plate present in Tornaiüa is, according to 

 recent observations, also found in the larvaj of Echinoderms — e.y., in 

 Antedon — although in a greatly reduced condition. The ccelom seems to 

 be segmented in the Echinoderms as well as in the Enteropneusta— a 

 fact which is certainly of importance. However, it is precisely the 

 interpretation of the cojlom in Balanoglossus which is not yet adequate, 

 since the different portions of the intestine, from which it takes its 

 origin, are not fully understood. Unfortunately it must be admitted 

 that even yet the relationships of Balanoglossus are shrouded in dark- 

 ness. — K.] 



Literature. 



1. AüAssiz, A. Notes on the Embryology of Starfishes (Tornaria). 



Ann. Lyceum Nat. Hist. New York. Vol. viii. 1867. 



2. Agassiz, a. The History of Balanoglossus and Tornaiüa. Ment. 



Amer, Acad. Arts and Sciences. Vol. ix. 1867. 

 ^ — 5. Bateson, W. Early and Later Stages in the Development of 



Balanoglossus. Quart. Jour. Micr. Set. Vols. xxiv. — xxvi. 



1884—1886. 

 5a. Bateson, W. The Ancestry of Chordata. Quart. Jour. Micr. Sei. 



Vol. xxvi. 1886. 

 .6. Fewkes, J. W. On the Development of Certain Worm Larvae. Bull. 



Mus. Comp. Zu'öl. Harvard Coll., Cambridge, Mass. Vol. xi. 



1883 — 1885 (description of a Tornaria found at Newport). 



7. GiARD, A. Systematic Position of Balanoglossus. Jour. Hoy. Micr, 



Soc. Vol. ii. 1882. 



8. Goette, a. Vergleichende Entwicklungsgeschichte der Comatula 



Mediterranea. Arch. Mikr. Anat. Bd. xii. 1876. 



9. Koehler, E. Contributions ä I'etude des Enteropneustes. Inter- 



nat. Monatsschr. Anat. u. Hist. Bd. iii. 1886. 

 10. Koehler, K. Sur la parente du Balanoglossus. Zool. Anzeiger. 



Jahrg. ix., No. 230, p. 506. 1886. 

 11.. KowALEVsKY, Alex. Anatomie des Balanoglossus delle Chiaje. 



Mem. Acad. St. Feiersbourg. Ser. 7, tom x. 1867. 



12. Marion, A. F. Etudes Zoologiques sur deux esp^ces d'Entero- 



pneustes, etc. Arch. Zool. e.vper. et gen. Ser. 2, tom. iv. 1886. 



13. Metschnikoff, E. Untersuchungen über die Metamorphose einiger 



Seethiere. I. Ueber Tornaria. Zeitschr. wiss. Zool. Bd. 

 xxii. 1870. 



