II. Systematic. 



a. SPECIES CAPTURED BV THE SIBOGA EXPEDITIOX. 



I. Genus Sagitta (sensu Langerhans iSSo). 



I . Sagitta Bedoti Béraneck. 



Ed. Béraneck. Les Chétognathes de la Baie d'Amboine. Revue Suisse de Zoölogie. 



Tomé III, p. 137. 

 Sagitta polyodon Doncaster. 

 L. Doncaster. Chaetognatha: Fauna and Geography of the Maldive and Laccadive Archi- 



pelagoes, Vol. I, p. 209. 

 Sagitta bipunctata Aida [nee Quoy and Gaimard). 

 T. AlDA. Chaetognaths of Misaki Harbour. Annotationes Zoologicae Japonenses. Vol. I, p. 13. 



Characters. Head rather small; neck only slightly niarked when in contraction; a 

 very slight thickening of the epidermis at the neck, but no real collarette. Body firm and 

 moderately transjjarent in formalin. Longitudinal muscles strong but narrow; lateral lields rather 

 large. Body thickest for about the middle ihird of its length, tapering sHghtly and gradually 

 forvvards, more rapidly backwards, generally with a siidden diminution at the tail sejjtum. Tail 

 segment about 21 to 35 per cent. of the total length. 



Anterior lins long, much widest posteriorly, and diminishing rapidly anteriorly; they nearly 

 or quite reach the abdominal ganglion. Po.sterior fins broader than the anterior, of about the 

 same length as the anterior; more on the tail than on the trunk, widest well behind the septum, 

 reaching nearly (? quite) to the vesiculae seminales. 



Jaws broad, not very strongly curved; tip .short, " thick, obtuse. Anterior teeth closely 

 set, broad below, small. Postcrior tceth very numerous, narrow, very closely set; the series 

 curves from the dorsal to the ventral surface towards the moulh as in iiiacrocephala. The points 

 of both sets of teeth small and obtuse: l>olh have a dark brown colour in the older .specimens. 



Vestibular ridge terminating externally in a wdl-marketl rather sharp process, and pro- 

 duced into fairly regular numerous acute prominences. Corona ciliata slightly sinuous, extending 

 from a half to about two-thirds of the distance between the head and the abdominal ganglion. 



The tips of the newer jaws are in some specimi-ns distinctly curved, l)ul 1 have never 

 seen them quite so hooked as in Béraneck's figure (PI. 1\', fig. 10). The .same author figures 



