THE PLUMULARID.E. 15 



agree with the figures of Kirc?ienpaueria. ] Although this group is statoplean, so far as its nemato- 

 phores are concerned, it is allied by every other character both of trophosome and goiiosoine to 

 the most typical eleutheroplean geuus. 



In many Eleutheroplea the mesial nematophore is fixed and not free; for example, Fliniuil<n-i 

 clarkei (fig. 38), P. deudritica, Monostcechas quadridens (fig. 41), and lluloptvris carintit/i (fig. 50). 

 According to Bale- this is true of at least half of the Australian species. Both the supracalycine 

 and mesial nematophores of Hulopterix airinata are fixed, and the species ia therefore literally 

 statopleau, although its relationship with the eleutheropleau forms is evident. In the remarkable 

 geuus Guttya Albnan the single species has immovable mesial nematophores aiid movable 

 supracalycine nematophores. 



It will thus be seen that uo hard and fast liue can be drawn between the two great groups of 

 Plumularidee on the basis of the fixed or free condition of the uematophores. The monothalamic 

 and bithalamic condition affords, perhaps, a better basis, although, as we have seen, it also has 

 exceptions, which, however, would be reduced if those species properly belonging to Kirchcnpaueria 

 were placed in that genus, which Bale considers statoplean. The best character, perhaps, that 

 has yet been suggested is the one mentioned by Bale, who says that, with a single probable excep- 

 tion, the supracalyciue nematophores are attached to the hydrotheca> in the Statoplea and not in 

 the Eleutheroplea. 



The most common form of free nematophore is that found in Antenniilaria, Anteitiiopxis, and 

 most species of Plum uhiria (fig. 37). It is trumpet-shaped in outline, the small end of the trumpet 

 being attached by a movable joint to the hydrocaulus, and the large end or "bell'' being distal, 

 the internal ridge being at the junction of the bell and the handle. The attachment is by means 

 of an exceedingly slender pedicel in some species; for example, Antennopxix din tans, Schizotricha 

 parvula (fig. -A3), and Potyplumularia armata (tig. 40). In such species the nematophores are apt 

 to be broken off and lost. In nearly all cases where the supracalycine nematophores are trumpet- 

 shaped, the mesial and cauline nematophores have the aperture oblique, so as to face more or less 

 toward the hydrocladinm or stem (fig. 44). 



The variations in size and shape of the free nematophores can best be understood by consult- 

 ing the accompanying figures made with the camera lucida, all being magnified to the same 

 degree, unless otherwise noted in the explanation of the figures. It will be seen that the varia- 

 tion in size is very great, for example, between the nematophores of Hchizotrirlia purrttla (fig. 43) 

 and Schizotricha dichotoma (fig. 44); and the difference in shape is equally remarkable, for exam- 

 ple, between Diplopteron quadricorne (fig. 48) and Plunntlttrin clarkel (fig. 38). So far as I have 

 been able to ascertain, none of the free nematophores have more than a single external opening, 

 and that is always terminal. It is also noteworthy that the hydrotheca- of the Eleutlieroplea 

 never have apertures on their anterior faces for the admission' of the lengthened processes of the 

 sarcostyles. 



There is often a distinct difference between the supracalycine, mesial, cauline, and gouosomtil 

 uematophores in the same species; for example, referring to the nematophores of Monostnchnx 

 quadridens (figs. 39-41), we see that the supracalycine nematophore is bell-shaped, with a horizon- 

 tal aperture; the mesial nematophore is curved, with an oblique orifice, and is firmly articulated 

 to the hydrocladiuin by a broad base, and the cauliue nematophore is longer, still more curved, 

 with an oblique orifice and a much narrower base. The uematophores of 1'lumtilaria darkei pre- 

 sent a similar series of differences. In most cases the gonosomal nematophores resemble the can- 

 line. The goiiosoine of Sciurella indivisa Allmau is protected by a number of trumpet-shaped 

 uematophores disposed in a semicircular manner, all borne on hollow lateral processes, springing 

 from the distal end of the gouaugium. 



Although the uematophores may be accidentally absent, they are probably normal to all 

 plumularians. The two classes, mesial and cauline, are present in all species known to me. The 

 supracalycine pair is absent in the genus Azyt/oplon, and in those species of Plumulur'nt which I 

 have suggested should go into the geuus Kirehenpaueria. Gonosomal nematophores are present 

 in all Phunularidie except certain species of Hitliconinria. 



1 Further Notes oil Australian Hydroids, with Descriptions of some Now Species. Proceedings of the Koyal 

 Society of Victoria, 1*93, p. 107, pi. vi, figs. 4-7. 



2 The Genera of the Pluuiulariida-, with observations on various Australian Hydroids. Melbourne, 18*ii, p. 7. 



