176 THE VOYAGE OF H.M.S. CHALLENGER. 



umbrellas of the sterile medusomes were separated from the appertaining siphons, and 

 both so dislocated, that the former migrated upwards and together composed the 

 nectosome ; whilst the manubria with the tentacles remained in the cormidia, composed 

 of clustered sexual medusomes or gonophores. 



The cormidia of the Polyphyidae are ordinate and monogastric, as in all other 

 Calyconectae, separated by free internodes of the stem, of equal length. Each cormidium 

 contains a single siphon and one tentacle, besides a group of clustered gonophores. 

 These are sometimes of one sex in each cormidium, so that this is diclinic. The corm 

 itself is monoecious, male and female cormidia occurring on the same stem ; usually the 

 androphores occupy the lower or distal part, the gynophores the upper or proximal part 

 of the siphosome. At other times the cormidia are monoclinic (composed of gonophores 

 of both sexes) as described by some authors (Kolliker, 4, and Weismann, 1883, p. 194). 



The general rule, that the cormidia are ordinate in all polygastric Calyconectae, has 

 perhaps a single exception in Poli/phijes. The clustered gonophores are here separated 

 from the base of the siphon by a small interval, and this seems to become larger in some 

 species, so that the cormidia may be described as alternate (or even irregular), the sterile 

 medusomes (siphon and tentacle) alternating with the fertile (gonophores), just as in 

 many Pkysonectas (Agalma, Agahnopsis, &c). This is perhaps the case in the 

 Mediterranean form described by Kolliker as Hippopodius neapolitanus (4, Tab. vi.), and 

 in a similar South Atlantic form, an incomplete specimen of which I observed in a bottle 

 from the Challenger collection (from Station 325), and which I have called provisionally 

 Polypliyes dinsolutus (95, p. 36). The preservation of this fragment, however, was not 

 sufficiently good to furnish confirmation of that statement, and since the description of 

 Kolliker has not been confirmed by later authors, it may be that an accidental error 

 occurred, and that the cormidia are always ordinate as in the common Hippopodius. 



Sipihons (fig. 1, s). — The polypites of the Polyphyidae are in general of the same shape 

 as in the other Calyconectae. The pedicle arising from the siphosome is sometimes longer, 

 at other times shorter or even rudimentary. The basigaster is subspherical or ellipsoidal, 

 its thickened exoderm full of cnidocysts. It is separated by a pyloric valve from the 

 ellipsoidal or spindle-shaped glandular stomach, which passes over without a sharp 

 boundary line into the long and very contractile proboscis. Sometimes these parts are 

 very prolonged and vermiform. The distal mouth is small and simple, but may be 

 expanded in the form of a circular suctorial disc. 



Tentacles (fig. 1, t). — The single tentacle, which is attached to the base of each siphon, 

 is very long and thin, beset with a series of very numerous tentilla. Each tentillum 

 (fig. 8) is composed of a long pedicle, a roundish cnidosac, and a cylindrical terminal 

 filament ; the latter is often coiled up spirally. The cnidosac is relatively small, ovate, 

 ellipsoidal or subspherical, often coloured by yellow or orange pigment. Its cnido-battery 

 is placed in form of a curved band along the convex dorsal side of the cnidosac, and 



