PLUMULARIA MEGALOCEPHALA. 31 



flank the hy(]i'otheca on each side ; mesial nematophores, one at the distal 

 and one at the proximal side of each hydrotheca. 

 Gonosome not known. 



Off Boca Grande, from a depth of 105 fathoms. 



The abruptly attenuated distal portion of the internodes of the pinnae 

 is sufficient to distinguish this species. The internodes of the stem are 

 short, and the pinnae are in consequence close set, resembling in this respect 

 those of P. filicvla. In the stem each internode carries two nematophores 

 which are placed laterally and alternately, and one pair of nematophores 

 which is borne by the lateral process. 



Plumularia megalocephala. 

 PL XIX. Figs. 1, 2. 



Tropliosome. — Hydrocaulus irregularly branched, not fascicled ; pinnte 

 alternate, each borne close to the distal end of an internode of the stem, 

 where it is supported on a long stout process of the internode ; proximal 

 internode of pinna short and destitute of hydrotheca; following inter- 

 nodes longer, every alternate one carrying a hydrotheca, and slightly 

 longer than the others. Hydrothecae small and shallow, each borne near 

 the middle of its internode, and supporting a very large hydranth. Besides 

 the supracalycine pair of nematophores, each hydrotheca-bearing internode 

 carrying a single mesial nematophore at the proximal side of the hydro- 

 theca ; intervening internode carrying two mesial nematophores, and short 

 basal internode carrying one. 



Gonosome not known. 



Off Alligator Reef, from a depth of 14 fatliouis. 



The specimens from which the description has been written were im- 

 perfect, and the height to which they had attained could not be determined 

 with certainty, but it was probably about two inches. The internode 

 intercalated between the hydrotheca-bearing internodes was sometimes 

 present, sometimes absent, and was of variable length. The internodes 

 of the stem carry two nematophores placed laterally and alternately, and 

 one or two pairs on its lateral process. 



Some of the hydranths in the specimens were sufficiently well preserved 

 to afford a sketch of their outline. They are of enormous size in com- 

 parison with the hydrothecas, into which they could never have been 

 retracted. The very large pear-shaped body was supported on a slender 

 stalk, the only part which lay within shelter of the hydrotheca. 



