PHYSOPHORA. 81 



tlian this, but it is probalile that in the adult organ the convohitions of the lateral canals 

 are even more complicated. 



Kolliker considers the lower enlarged end of the stem of Physophora to be a simple 

 dilatation of the coenosarc ; but Vogt affirms that it is not only enlarged, but bent upon itself, 

 so that its discoid form is more apparent than real ; and he adds, that the more developed 

 appendages are always situated at the distal end of this coiled enlargement of the coenosarc ; 

 tjie young buds of the hydrocysts and polypites being situated at its proximal end, or 

 where it joins the narrow stem-like portion of the coenosarc. 



Philippi states that, in P. tetrasiicha, a membranous fold runs down one side of the axis, to 

 which, without doubt, the nectocalyces were attached. Below, the axis becomes somewhat 

 wider, makes a turn, and ends in a tolerably large vesicle, which, in the living animal, is 

 hidden by the appendages. It is placed not in the middle, but on one side ; upon the other 

 side it exhibits a wide aperture surrounded by a plaited membranous fold like a collar. 

 Philippi supposes that this aperture is the mouth, and the cavity into which it leads 

 the stomach, wherein he is undoubtedly mistaken. Externally, he found no trace of the 

 attachment of the hydrocysts, but, from the middle line below, the racemose reproductive 

 organs depended. 



In my notes upon the small Phi/sopJiorce, I find it stated that the bulbous expansion 

 of the stem ends below in a sort of solid papilla, in which there were no indications of any 

 inferior aperture ; and on this last point Vogt and Kolliker are also agreed against PhiUppi. 



According to Philippi and Kolliker, the hydrocysts are arranged, most externally, in 

 a complete circle around the inferior enlargement, and internal to these are the polypites, 

 with a tentacle attached to each. The male and female reproductive organs are attached in 

 pairs beside (neben) the polypites. According to Vogt, the hydrocysts are external, 

 the polypites internal, and the groups of reproductive organs lie between them. 



In my specimens the hydrocysts were external, the polypites internal ; but I can say 

 nothing about the reproductive oi'gans, as they were not developed. 



The hydrocysts are closed sacs with pointed apices and broad bases, by which 

 they are fixed into the coenosarc. Vogt says, " L'extremite par laquelle le tentacule est 

 fixe au disque, est taillee comme un bee de plume de maniere a s'adapter a la surface arrondie 

 du disque. Cette extremite n'est point fermee ; elle s'adapte facilement sur une ouverture 

 conduisant du disque dans la cavite du tentacule. En arrachant ce dernier on remarque 

 qu'un fil de matiere elastique entre dans le disque meme et sert ainsi d'attache " (p. 45). 



In my specimens this was by no means the way in which the hydrocysts were connected 

 with the coenosarc, but the broad bases of the former coalesced completely with the wall of 

 the latter (fig. 3), which extended inwards so as to leave only a narrow, oblique, valvular 

 aperture of communication between the cavity of the hydrocyst and that of the coenosarc.^ 



* PbiUppi (p. 61) describes the hydrocysts as having "flattened articular surfaces." "In the 

 middle of the articular surface is a small knob (licicker), probably the point of attachment, and down 

 from its upper part depends a fine thread, which, when extended, is longer than the hydrocyst, 

 but is often spirally coiled up, and then is hardly a line long" (p. 61). According to this observer, 

 the hydrocysts are true "prehensile arms" (Fangarrae), for, on placing the end of a forceps in their 

 neighbourhood, " they all seized it, held it fast, and loosened their liold only in a couple of seconds." 



11 



