AMERICAN HYDROIDS. 127 



KEY TO AMKRICAX SPECIES OF THE GENUS HALICORNARIA. 



i Mesial iifiuatophorn not projecting far above margin of hydrotheca. II. speciosa 

 Cauline nematovhoxea not very large . -ft. 



' < Mesial nematophore projecting iar above margin of hydrotheca. U. longicauda 



Cauline nematophores very large and bilobed H.rariabilis 



HALICORNARIA LONGICAUDA, new species. 

 (Plate XXXIII, figs. 4, 5.) 



Trophosomc. Colony unbranched, attaining a height of about (> inches; stem not fascicled, 

 divided into regular iuteruodes, each of which bears a hydrocladium; liydrouladia closely approxi- 

 mated, alternate, divided into rather short internodes; no septal ridges. Hydrothecie moderately 

 deep, closely approximated, with their long axes forming a wide angle with the axis of the hydro- 

 cladium, and their distal half free; aperture nearly vertical, with two shallow sinuatious on each 

 side, and a very strong anterior flexure and intrathecal ridge; snpracalycine nematophores stout, 

 triangular iu outline, not reaching the level of the top of the liydrotheca ; mesial nematophore very 

 long, reaching far beyond the top of the hydrotheca, distal end curved slightly upward; two aper- 

 tures, one at the end and the other immediately above the top of the hydrotheca; cauliue nemato- 

 phores of moderate size, one on each side of the base of each hydrocladium. 



Gonosome. Not known. 



Distribution. Albatross Station 2147, lat. X. 9 32', long. W. 79 55'; depth, 34 fathoms. 



The mesial nematophore of H. longicauda is longer than any other found among American 

 Plumularidie, reminding one of some of the striking forms found in Australia. 



Type slides. Cat. No. 18701, U.S.N.M.; Cat, Nos. 15403, 15404, Mus. State Univ. Iowa; also 

 in the collection of the author. 



HALICORNARIA SPECIOSA Allman. 



(Plate XXXIII, figs. 1-3.) 

 Halicornaria sprciom ALLMAN, Mem. Mus. Couip. Zool., 1877, V, No. 2, p. 54, pi. xxxiv. 



TrophoKomf. Colony unbranched, attaining a height of about 12 inches; stem not fascicled, 

 divided into regular short internodes, each of which bears two hydrocladia; hydrocladia nearly 

 opposite on the basal part of the colony, and sub alternate on the distal portion, divided into 

 regular short internodes by rather oblique nodes; septal ridges wanting. Hydrothec;e closely 

 approximated, not deep; aperture wide, its axis forming an angle of 45 degrees with that of the 

 hydrocladiuin; margin with three broad, shallow siuuations, or lobes, on each side; intrathecal 

 ridge anterior, perpendicular to the axis of the hydrotheca and slightly turned upward at its 

 distal end; supracalycine nematophores stout, scarcely overtopping the hydrotheca; mesial nema- 

 tophore adnate nearly to its distal end, which attains the level of the top of the hydrotheca; 

 cauline nematophores small, one on either side of the base of each hydrocladium. 



Gonosome. Gouaugia obcouic, with an abruptly truncated distal end; borne singly at the 

 bases of the hydrocladia. No protective contrivances of any kind. Sometimes the gonaugia are 

 almost hemispherical in shape. 



Distribution. Double-headed Shot Key, Florida; depth, 4 to 5 fathoms; Albatross Station 

 2640, lat. N. 25 05', long. W. sO 15'; depth, 50 fathoms. 



This species, with some others of the same genus, is remarkable from the fact that each stem 

 joint bears two hydrocladia. The specimens secured by the Albatross are much larger than those 

 found by Count Pourtali-s and came from considerably deeper water. They differ slightly from 

 the type, having two instead of three well-defined marginal teeth on each side, and not having 

 the anterior profile straight. 



Type. In the Museum of Comparative Zoology, Cambridge, Massachusetts. 



HALICORNARIA VARIABILIS, new species. 

 (Plate XXXIII, (i-ts. li-11.) 



Trophosome. Adult colony piunately branched, attaining a height of about 5 inches; 

 stem not fascicled, divided into rather short internodes, each of which bears a pair of hydro- 

 cladia; hydrocladia nearly opposite on the proximal part of the full-grown colony, and alternate 



