22 NEW INVERTEBRATA FROxM 



and extend outward at an angle to their attachment. They 

 .are capable of more or less movement, and sometimes act 

 as flappers in the propulsion of the animal. 



Each hydrophylliuni is elongated, leaf-like, thin, pene- 

 trated by a median canal. The outer surface of the hydro- 

 phylliuni is crossed by lines of lasso-cells, the prominent 

 rows of these structures extending longitudinally across 

 the outer surface of the bract. On either edge of the cover- 

 ing scale, opposite each other and midway between the 

 attachment and free extremity, there is a notch or inden- 

 tation. The polyp-stem, or that region of the axis of the 

 Siphonophore which carries the polypites, tasters, sexual 

 bodies and hydrophyllia, is reduced in length and enlarged 

 into an inflated bag, continuous with the float. 



The tasters are long and filamentous, very flexible, and 

 have a slightly pinkish color. Their tentacles, if they ex- 

 ist, which is doul)tful, are very small and rudimentary. 



A single, immature polypite was observed, and at this 

 stage the Athorybia is monogastric. This single polypite 

 has an open mouth, with trumpet-shaped lips. Three long 

 tentacles were observed, each bearing tentacular knobs. 

 One of the tentacles probably arises from the single l)oly- 

 pite, the others from immature oi'gans of the same char- 

 acter. Clusters of half-developed tentacular knobs were 

 observed on the polyp-stem or polyp-sac, for the polyp-stem 

 is here reduced to a globukir enlargement, at the base of 

 the larger polypite. 



Each tentacidar knob, fig. 2, consists of a peduncle, a 

 saccuius, an involucrum, two terminal filaments and a 

 median vesicle. The peduncle, or base of attachment to 

 the tentacle, is long and flexible, highly contractile, trans- 

 parent and colorless. The involucrum forms a button-like 

 structure, not unlike an enlargement of the peduncle at its 

 distal end. It is prolonged on one side into an apex, or 



