THE THECOSOMATA AND GYMNOSOMATA 

 OF THE SIBOGA-EXPEDITION 



BY 



J. J. TESCH 



Utrecht. 



W i t h s i X p 1 a t e s. 



INTRODUCTION. 



The occurrence of Thecosomata and Gymnosomata, composing together the group ot 

 the so-called "Pteropoda", in the seas now explored by the Siboga, has been stated only a 

 few times. 



Though OoY and Gaimard, on the voyage of the Astrolabe, already described several 

 species from Amboina, yet the indications and figures of these zoologists are too fragmentary 

 and incomplete, to throvv some more Hght on the knowledge of these animals. 



Afterwards it has been, properly speaking, only the Challenger, which collected specimens 

 from a few places (North of New-Guinea and off the Philippines). Moreover I can mention a 

 Note of V. ScHÉELE (list of literature, Munthe 1886). I have also seen some specimens of 

 Thecosomata from the Sunda Straits and Java Sea (Utrecht Zoological Museum). 



In a study on the geographical distribution of such essentially pelagic animals as the 

 "Pteropoda" are, I have preferred to take a larger field of exploration than the area in which 

 the Siboga-material was collected. 



For that reason I have accepted the Australasian province, proposed by Pelseneeé ^) 

 (almost agreeing with the Indian province of Keferstein ^), viz. the East-Indian Archipelago, 

 the China Sea, the Philippines and the seas of North-Australia. 



i) Challenger Report. LVIII, p. 62. 

 2) In Bronn's Thierreich. Bd. III, p. 

 SIBOGA-EXPEDITIE UI. 



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