390 



EMBRYOLOGY 



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

 in them organs of different phylogenetic origin (Spengel). The ccelom 

 of the Enteroimeusta exhibits other conditions than in the Chordata. 

 The probability of the relationship of Balanoglossus to the Echinodenm, 

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

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

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

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

 recent observations, also found in the larvs of Echinoderms — e.g., in • 

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

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

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

 interpretation of the coelom 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. Agassiz, a. Notes on the Embryology of Starfishes (Tornaria). 



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



2. Agassiz, A. The History of Balanoglossus and Tornaria. Mem. 



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

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



Balanoglossus. Quart. Juur. Micr. Sci. Vols. xxiv. — xxvi. 



1884—1886. 

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



Vol. xxvi. 1886. 

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



Mus. Comp. Zool. Harvard Coll., Cambridge, Mass. Vol. xi. 



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



7. GiAiU), A. Systematic Position of Balanoglossus. Jour. Boy. Micr. 



Soc. Vol. ii. 1882. 



8. GoETTE, A. Vergleichende Entwicklungsgeschichte der Comatula 



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

 a. KoEHLEK, K. Contributions a I'^tude des Enteropneustes. Inter- 

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



10. KoKHLEii, 11. Sur la parente du Balanoglossus. Zool. Anzeiger. 

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



lU KowALEvsKY, Alex. Auatomie des Balanoglossus delle Chiaje. 

 Mem. Acad. St. Petershourg. Ser. 7, torn. x. 1867. 



12. Mahion, a. F. Etudes Zoologiques sur deux especes d'Entero- 



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



13. Metschnikofi-, E. Untersuchungen iiber die Metamorphose einiger 



Seethiere. L Ueber Tornaria. Zcitschr. iciss. Zool. Bd. 

 xxii. 1870. 



