REPORT ON THE SIPHONOPHOR^. 331 



Salacia polygastrica, n. 'sp. (PI. XXV.). 



Habitat. — Tropical Atlantic; Station 338, March 21, 1876; lat. 21° 15' S., long. 

 14° 2' W.; depth, 1990 fathoms. 



Corm. — The trunk of the single specimen observed had in the expanded state a 

 length of 120 to 150 mm., and bore about eight developed cormidia, besides the same 

 number of young and undeveloped ones in the proximal portion, beyond the apical float. 

 The ordinate cormidia were separated by long naked internodes. The cylindrical trunk 

 was filiform and had a diameter of only half a millimetre, but exhibited a high degree of 

 firmness and elasticity. Although it was much contracted in the spirit bottle, it was 

 possible, by softening it gradually with water, to make it so elastic that it could be 

 extended to that degree which is figured in PI. XXV. fig. 1. 



Pneitmatophore (fig. 1, lateral view; fig. 2, horizontal section, near the pylorus 

 infundibuli ; fig. 3, apical view, fore-shortened). — The large float is ellipsoidal, 10 mm. 

 long, 6 mm. broad. Its apex is truncate, with a central dimple, which contains the 

 stigma or the apical opening for the emission of gas (fig. 3, po). In the apical view 

 (fig. 3) strong radial muscles (pm) are visible, which open the stigma; beyond them lie 

 the circular muscles which compose the sphincter closing it. This eye-like sphincter is 

 surrounded by a corona of eight roundish radial lobes, covered by dark pigment-granules. 

 I could not make out the true nature of these lobes (fig 3, seen from above, and fig. 1, 

 in profile). The uppermost part of the pericystic cavity appeared to be divided by 

 eight radial septa into eight radial pouches opening below ; but the dark pigment 

 covering them (much richer than is represented in fig. 3) prevented their distinct 

 recognition. The apparent septa may be only radial folds. 



Pneumatocyst. — The chitinous air-flask is spindle-shaped and occupies the upper 

 two-thirds of the float-cavity ; it exhibits two openings on the two poles of its axis, the 

 apical stigma for the emission of gas (fig. 3, po), and the basal pylorus infundibuli (fig. 2, 

 py), through which the gas, secreted by the exodermal epithelium of the infundibulum, 

 enters into the cavity of the air-flask. The outside of the cuticular pneumatocyst is 

 covered by its matrix, the exodermal pneumatosac ; this has an annular constriction round 

 the pylorus (fig. 2, py), and forms beyond it a hemispherical cavity, the infundibulum or 

 pneumatochone. From this arise eight radial bunches of hypocystic villi (figs. 1-3, pv), 

 which fill up the greater part of the hypocystic cavity. Each vdlus is composed of a 

 few colossal exodermal giant-cells (1 to 2 mm. in diameter) and of a ciliated epithelium 

 of small entoderm cells covering them (as in PI. XXIV. fig. 6). 



Cormidia. — Each ordinate polygastric cormidium (fig. 4) is a botryoidal cluster 

 composed of about ten to twenty siphons and gonodendra, each siphon provided with a 

 long simple tentacle. Four to six siphons only seem to be fully developed in each 



