78 



AMERICAN IIYDRO1DS. 



Gonoitome. Gonangia ovate, with large terminal apertures, borne on the sides of the proximal 

 nematophoroas branches, and each bearing two nematophores near its base. 



Distribution. AIb<ttrons Station 2415, lat. N. 30 44', loiig. W. 79 2(5'; depth, 440 fathoms; 

 Station 20(50, lat. N. 30 48', long. W. 79 49'; depth, 270 fathoms; Station 2007, lat. N. 30 53', 

 loug. W. 79 43'; depth, 273 fathoms; Station 2(568, lat. N. 3(P 59', long. W. 79 39'; depth. 294 

 fathoms; Station 2(5(59, lat. N. 31 09', loug. W. 79 34' ; depth, 352 fathoms. 



Type sli:lvs.Ua,t. Nos. 18570, 18577, 18578, U.S.N.M.; Cat. No. 11713, Mus. State Univ. Iowa; 

 also in the collection of the author. 



SCHIZOTRICHA Allman (modified). 



,Sc/ii.-/nV/m AM. MAN, Challeniji-r Report, 1X8H, VII, Pt. 20, p. 2K. 



Trophosome. Ilydrocladia pinnately disposed, branching once, twice, or oftcner; bifurcating 

 beyond the first internode, at least in the mature colony. 



(ioHoxoiiic. Gonangia springing from the stem or hydrocladia. It is not easy at first sight to 

 distinguish the trophosome of this genus from that of the genus Polyplumularia of Sars, in which 

 each hydrocladium bears an accessory hydrothecale ramulus, which might be mistaken for a fork 

 or a branch of the hydrocladium itself were it not that the accessory branch is much smaller than 

 the hydrocladium from which it springs. 



The gonosome of Polyplumularia springs from the main branches and not from the hydrocladia, 

 as in the case in IScliizotrirliii. 



A study of the new species herein described seems to indicate that the forking of the hydro- 

 cladia is simply one of the many strange modifications found in this group for the protection of the 

 gouaugia, as it is often absent in those parts of specimens which are not furnished with the 

 reproductive persons. If this is true, it is evident that the forking can not in strict propriety be 

 regarded as a character of the trophosome, but an accessory part of the gonosomal system. 



Distribution of American species of the genus Schieotricha. 



KKV TO AMERICAN SPECIES OF SCHIZOTRICHA. 



Hydrothecie about twice as deep as wide .S. dichotoma. 



Hydrothec;r not deeper than wide: 



Stein not fascicled; one intermediate internode between adjacent hydrotucc.-i' S.parrula. 



Stem not fascicled; two intermediate internodes between adjacent li\drothee;e S.tein-llu. 



Stem fascicled; intermediate internodes normally absent S.gracillima. 



SCHIZOTRICHA DICHOTOMA, new species. 

 (Plate XV, figs. 1-4.) 



Trophosome. Colony a single pinnate stem, attaining a height, in incomplete specimens, of 

 about 5 inches; stem fascicled; hydrocladia alternate, not fascicled, directed forward as in Plu- 

 iii ii la rin ijeminatd Allman, each giving rise at its second internode to a bifurcation, one of the 

 resultant branches again forking, thus making four ultimate branches to each hydrocladium, 

 three being from one of the primary branches, the other being undivided with distant and irreg- 

 ularly disposed nodes, each internode bearing several hydrothecse; the branched division of the 

 hydrocladium has irregularly disposed hydrotheca- and will be more minutely described under the 

 gouosouie. Ilydrotheca-. on unbrauched division of hydrocladium large, closely approximated, 

 very deep, adherent throughout their length to the hydrocladium; margin almost straight in 



