HYDROIDS OF THE HAWAIIAN ISLANDS. 
941 
proximal and distal set and in the fact that the pedicel is entirely naked. The character of the stem 
is unique in that it combines a true fasciculation with the presence of external coenosarc. The dactyl- 
ozooids, if such they are, are also unique in the apparent absence of well-defined nematocysts. It is 
unfortunate that the gonosome is absent, as that would in all probability furnish clews to the true 
affinities of this strange hydroid. 
Family CLAVID4}. 
Trophosome . — Stem branched or unbranched. Hydranths with scattered filiform tentacles. 
Gonosome . — Gonophores either in the form of free medusae or producing the sexual products in 
fixed sporosacs. 
Allman, in his Monograph of the Gymnoblastic Hydroids, published in 1871, places the genus 
Corydendrium in the family Turridse, under a mistaken idea that the only species known, ( '. parasiticum, 
bore medusae with simple radial canals and simple tentacles. In 1883 Weismann published his Ent- 
stehung der Sexualzellen bei den Hydromedusen, in which he points out Allman’s mistake and shows 
that Corydendrium produces no medusae at all (p. 40). Weismann, however, does not attempt any 
general classification of the hydroids and does not correct the systematic error of Allman. 
In 1897 Dr. Karl Camillo Schneider published his “ Hydropolypen von Rovigno nebst Uebersicht 
fiber das System der Hydropolypen im Allgemeinen,” in which he proposes a general revision of the 
classification of the Hydroida, the result being the throwing of numerous well-established families 
together and rendering the task of the workers in the Hydroida more perplexing than ever. He 
places the 20 families of Gymnoblastea recognized by. Allman in 4 families. He does not regard 
Corydendrium parasiticum as representing a distinct genus, placing it in the old genus Clara. 
The present writer thinks that Doctor Schneider is correct in placing this species in the Clavidse, 
but that he is in error in failing to recognize the validity of the genus Corydendrium. 
Genus CORYDENDRIUM. 
Trophosome . — Colony branched and fascicled. Hydranths with scattered filiform tentacles. 
Gonosome . — Gonophores borne on the stem and branches, in the form of either medusse or fixed 
sporosacs. 
Corydendrium corrugatum Nutting, new species. 
(PL ii, fig. 2; pi. vii, figs. 5, 6, 7.) 
Trophosome . — Colony attaining a height of about 5 inches. Stem and branches fascicled, the 
former being nearly straight or irregularly but not abruptly bent, and bearing branches that are 
opposite, subopposite, or alternate, the whole forming a roughly pinnate structure. Branches often 
showing a 'well-marked annular constriction near their origins and bearing on their anterior aspect the 
hydrophore-like structures within which the hydranths retract. These hydrophores are inclined 
alternately to the right and left, are not very distant, and are cylindrical with a round terminal orifice, 
an even margin, and are usually distinctly corrugated with deep irregular annulations. Hydranths 
large, with elongate pyriform body and very numerous filiform tentacles emplanted over the surface 
so thickly that they almost entirely conceal the hydranth body. Proboscis very dilatable, as shown 
in figure 7. 
Gonosome. — Unknown. 
Distribution . — Station 3828, south of the island of Oahu, 319 fathoms; station 4077, northeast coast 
of the island of Maui, 99 fathoms. 
The hydrocaulus of this species is much more thick and rigid than in 0. parasiticum, and the 
hydrophores are more distinct and are decidedly corrugated. 
Corydendrium minor Nutting, new species. 
(PI. ii, fig. 1; pi. vii, figs. 8, 9.) 
Trophosome . — Colony growdng on a creeping root-stock, parasitic on a species of Lafo'ea, and attain- 
ing a height of about one-half inch. Stem and main branches fascicled, the latter being irregularly 
disposed and giving forth alternate branches. The ultimate branchlets are not fascicled, but the 
perisarc is strong and tubular, ending abruptly at base of hydranths. Hydranths with an elongated 
