92 ■ AMERICAN HYDROIDS. 



SILICDXARIA ATLANTICA (Marktanner-Tumeretscher). 



Plate 25, fig. 5. 



Hypanthia atlantica Marktannee-Turneretscher, Hydroiden des k. k. naturhist. Hofmuseums, 1890, p. 211. 

 Silicularia atlantica Hartlaub, Die Hydroiden der magalhaensischen Region und chilenischen Kuste, 1895, p. 580. 



TropTwsome.^ — Hydrorhiza in the form of creeping, threadlike rootstock, sparingly branched 

 on the folds of a thallus of an alga. Pedicels 1 to 5 mm. long, about .18 mm. in diameter, with 

 thickened walls, with a globular amiulation separating it from the hydrotheca. Hydrothecse 

 with greatly thickened walls, their form greatly resembling that of Eucopella campanularia 

 •Ton Lendenfeld, margin strongly obhque; length .35 to 6 mm. and breadth across margin .3 to 

 .63 mm. 



Gonosome. — Female gonangia borne on short pedicels compressed above, reaching a height 

 of 2.7 mm. and a diameter of .67 mm. at the widest part. Male gonangia a^e much smaller 

 than the female and their pedicels usually longer; their length in the swollen part reaches 1.7 

 mm., and the pedicel .38. Their diameter is about .25 mm. 



The writer also describes the occurrence of one hydrotheca above another on the same 

 pedicel as figured by Mereschkowsky as occurring in Clytia poterium. 



Locality. — The type-specimen is from lat. 6° S.; long. 38° W.; collected by Dr. A. WoH. 

 No other specimens of this species have been reported. 



SILICULARIA REPENS (Allman). 



Plate 25, fig. 6. 



Hypanthea repens Ailman, Descriptions of some new species of Hydroida from Kerguelen's Island, Ann. Mag. Nat. 



Hist., ser. 4, vol. 17, 1876, p. 115. 

 Hypanthea repens Marktanner-Tubneretscher, Hydroiden des k. k. natm-hist. Hofmuseums, 1890, p. 211. 

 Silicularia repens Hartlaub, Die Hydroiden der magalhaensischen Region und chilenisclien Kilste, 1905, p. 572. 



Trophosome.^ — -Peduncles about one-fourth inch high, springing at intervals from a creeping 

 stolon, with a globular annulus just below the hydrotheca, but otherwise smooth. Hydrothecse 

 obconical with very oblique margin, their cavity forming distally a shallow cup, which is pro- 

 longed as a narrow cylindrical tube downward through the axis of the hydrotheca. 



Gonosome. — -Gonangia elongated, narrow, passing gradually into a short peduncle which 

 springs from the creeping stolon; colonies monoecious, the male gonangia surpassing in height 

 the hydrothecal peduncles, fusiform, opening on the summit by a narrow circular orifice; the 

 female shorter than the male, scarcely narrowing toward the distal extremity, where there is a 

 wide orifice. 



Habitat. — ^Swains Bay (Kerguelen). 



SILICULARIA HEMISPHERICA Allman. 



Plate 25, figs. 7-8. 



Silicularia hemispherica Allman, Challenger Reports, Hydroida, pt. 2, 1888, p. 27. 



Silicularia hemispherica Hartlaub, Die Hydi-oiden der magalhaensischen Region und chilenischen Kiiste, 1905, p. 57G. 

 Silicularia hemispherica Jaderholm, Hydroiden aus antarktischen und subantarktischen Meeren, 1905, p. 18. 

 Silicularia hemispherica Ritchie, Hydroids of the Scottish Nat. Antarctic Exped., 1906, p. 529. 



Trophosome.^ — Colony growing from a creeping rootstock which is thick-waUed and of 

 considerably greater diameter than the pedicels. The rootstocks do not lie parallel to each 

 other (according to Hartlaub). The pedicels vary from a little more than the height of the 

 hydrotheca to four times the height of the latter. They are thick-walled, and bear from one 

 to three deep annulations immediately below the hydrothecse. 



' No material of this species being at hand, the -writer takes the above description from the original by Marktanner- 

 Tumeretscher. 



^ In the absence of material representing this species the -writer quotes entire the original description of Allman. 



' Description made partly from a fragment of the type collected by the Challenger and partly from Hartlaub's 

 notes on specimens taken from Terra del Fuego. 



