THE PU'MULAKID.K. 79 



froiit, but cut away at tbe postero-latcral corners, making the front considerably higher than the 

 back; distance between hydrotheca' nearly equal to their length; supracalycine nematophores 

 borne on processes of the hydrocaulns and apparently capable of hanging down into the hydro- 

 thecal cavity; a single mesial uemutophore below each hydrotheca; cauline neiuatophores numer- 

 ous and irregularly distributed. 



(iiinoxome. Gonaugia borne on one of the forkings of the hydrocladiuin, almost globular, 

 opening terminal and round, peduncle short, armed with four nematophores. As before indicated, 

 I regard the branched division of the hydrocladium as morphologically a phylactogoninm com- 

 posed of three branches, one of which bears the gonangium and a few scattered hydrotheca-, one 

 being just above the origin of the gonangiiini; one of the other branches bears a few hydrotheca- 

 on its distal portion and the other bears a single hydrotheca on its distal end, but a great Lumber 

 of -nematophores on the side facing the gonangium: there is a hydrotheca at each forking of the 

 hydrocladium. 



Distribution. State University of Iowa, Bahama Expedition, Station 50; Pourtales Plateau, 

 200 fathoms. 



The remarkable structure which I here consider a phylactogonium may throw light on the 

 origin of phylactogonia in other groups. It here seems to be the hoiuologue of a branch of the 

 hydrocladium out of which a protective structure is produced by the suppression of most of 

 the hydrotheca- and the multiplication of the nematophores. The whole hydrocladium with its 

 modified branches is directed forward, so as to almost meet its fellow from the opposite side of the 

 stem, the two thus clasping the gonangia, as it were, and further securing their safety by bringing 

 into available proximity the six protective branchlets borne by the two hydrocladia. It is interest- 

 ing to note that in another specimen with less mature gonangia the pinna' are not directed forward 

 and apposed, but directed laterally, as usual among plumularians. The apposition may therefore 

 be merely a temporary position assumed to protect the matured gonangia. 



Still another specimen, associated with the last and apparently of the same species, has 

 unbranched hydrocladia, which are alternate and directed laterally. It may be regarded as a 

 specimen which has not yet attained the phylactogonia and indicates the correctness of the theory 

 advanced above. 1 



Type s/fV/tv*. Cat. Nos. 11710, 11711, 11712, 11714, Mus. State Univ. Iowa; Cat. Nos. 18.379, 

 18580, U.S.N.M.; also in the collection of the author. 



SCHIZOTRICHA PARVULA, new species. 

 (Plate XV, tig. 5.) 



Tropltoxonif. Colony attaining a height of about 1 inch, springing in a tuft of stems from a 

 common root stalk; stem not fascicled, divided into regular internodes, each of which bears a 

 hydrocladium on a process from its distal end; hydrocladia alternate, directed antero-laterally and 

 dividing into two brauchlets at the second internode; first internode bearing a hydrotheca near 

 its middle; second internode bifurcating to support the two branchlets into which the hydrocladium 

 is divided; branchlets composed of alternating hydrothecate and intermediate internodes, the 

 former being about twice as long as the latter. Hydrothecse distant, shallow, cup shaped, borne 

 at or just below the middle of the interuodes; supracalycine nematophores present; a mesial 

 neuiatophore below each hydrotheca, one on each intermediate internode and one at the bifurca- 

 tion of each hydrocladium; there is a cauliue iiematophore in the axil of each hydrocladium 

 and one on the opposite side of each interuode of the stem. 



Gonoaome. Gonangia elongated, oval sacs, borne in the bifurcations of the hydrocladia. 



Distribution. Allittroxx Station 2609, lat. N. 31 0!)', long. W. 79 34', 352 fathoms. 



Type slides. Cat. Xo. 18581, U.S.N.M.; Cat. No. 11709, Mus. State Univ. Iowa. 



1 In this connection see Fewkes's discussion of the guuus I'lrurocarpa in Bull. Mus. Coiup. Zool., VIII, No. 7, ]>. 1M6. 



