REPORT ON THE SJPHONOPHOR^E. 311 



are polygastric. The macrostelial Rhizophysidse (Pis. XXIII. , XXIV.) bear a single 

 siphon in each cormidium, as also do the brachystelial Epibulidse (PI. XXII. fig. 6). 

 The Salacidse exhibit a bunch of several siphons in each cormidium (PI. XXV. figs. 1-4). 

 The Physalidse, finally, bear on the ventral side of the shortened vesicular stem a 

 crowded group of numerous loose and polygastric cormidia, with a large number of 

 clustered siphons ; often larger and smaller polypites intermingled and arising from a 

 common pedicle, but the smaller Physalidse {Alophota, PI. XXVI. figs. 2, 3), and the 

 young forms of the larger species, bear on the ventral side of the trunk a simple series of 

 ordinate monogastric cormidia. 



Protosiphon. — -In many Cystonectse (or perhaps in all ?) the primary manubrium of 

 the larval medusome remains functional as the " primary feeding polypite," or the 

 protosiphon. It is the single siphon in the Cystalidae. In all young Physalidse the 

 protosiphon, placed at the basal pole of the inflated trunk and opposed to the apical 

 stigma, forms an independent cormidium (PI. XXVI. figs. 2, 3, su) ; originally it is 

 separated by a wide interval from the ventral group of the secondary cormidia, which 

 arise on the ventral side of the trunk, and bear the metasiphons (or the secondary 

 polypites). The latter alone afterwards produce gonodendra, not the former. So also 

 in the Epibulidse the protosiphon seems to remain as the basal siphon at the distal end 

 of the trunk. Its comparison with the manubrium of the primary medusome, or the 

 larva of the Cystonectse (Cystonula, PI. XXII. figs. 1-4 ; PI. XXVI. fig. l), shows us 

 that the axial trunk of the polygastric corms is only the basal part of the modified proto- 

 siphon, widely inflated in the Brachystelinise, extremely prolonged in the Macrostelinise. 

 Palpons. — All Cystonectse possess a great number of palpons (tasters, hydrocysts, or 

 mouthless polypites). These are usually cylindrical or spindle-shaped tubes with a 

 very contractile muscular wall, and a pointed and closed distal apex, often coloured. 

 They occur in three different forms, as sexual palpons, coronal palpons, and tentacular 

 palpons. 



Gonopalpons or Sexual Palpons are generally distributed, occurring in the gonodendra 

 scattered between the gonophores. Sometimes each branch of the clustered gonodendrou 

 bears a single gonopalpon (PL XXIII. fig. 8, gq) ; at other times several palpons (PI. XXV. 

 fig. 7, gq) ; those of the Physalidse (PL XXVI. fig. 8, q) are distinguished by the 

 possession of hepatic villi, which prove evidently that they are merely mouthless siphons. 



Coronal Palpons occur only in two families of Cystonectse, in the monogastric 

 Cystalidae and the polygastric Epibulidse (PL XXII. figs. 5, 6). They form a corona 

 around the base of the siphosome, beyond the pneumatophore, similar to that of the 

 Discolabidae and Anthophysidse (Pis. XL, XIX.). A.s in these latter, the coronal palpons 

 are not only organs of feeling and capturing, but also of protecting, and replace the 

 absent bracts. Their pointed distal end is armed with cnidocysts. 



Tentacular Palpons are peculiar to one family only, the Physalidse (PL XXVI. figs. 



