THE PLUMULARID^E. 83 



DIPLOPTERON LONGIPINNA, new species. 

 (Plate XVI, figs. 3, 4.) 



Trophosome. Colony of fragmentary specimen about 4 inches high, but judging from the thick- 

 ness of the stem and length of hydrocladia it probably attains a height of 1 foot or more; stem 

 fascicled ; hydrocladia alternate, closely set, borne on, opposite sides of the stem and directed later- 

 ally, with usually two distinct internodes on the proximal portion, followed by a few poorly 

 marked and distant nodes, which disappear altogether in the distal portion of the hydrocladium. 

 Hydrotheca; deep, subconical, less than their owu length apart, margins entire, but cut away 

 laterally and posteriorly so that the front of the hydrotheca is considerably higher than the back. 

 There is acauline hydrotheca at the base of each hydrocladium; a pair of lateral nematophores of 

 ordinary size borne on processes from the hydrocladium just above the middle of the hydrotheca; a 

 second pair of nematophores immediately above the margin of the hydrotheca and pendent within 

 its cavity; a third pair of nematophores is found about midway between the second and the base 

 of the next hydrotheca above. 



Gvnosome. Not known. 



Distribution. Lat. N. 24 10', long. W. 81 22', 200 fathoms. State University of Iowa, Bahama 

 Expedition. 



The portion of the type specimen obtained shows that this is a robust and large species. One of 

 the hydrocladia has an accessory hydrothecate ramulus. None of the others show this feature, 

 which is doubtless as inconstant as in Schizotricha, and probably is to be regarded as an accessory 

 portion of the gonosoine. 



Type slides. Cat. Nos. 11704, 11705, Mus. State Univ. Iowa; Cat. Nos. 18584, 18585, U.S.N.M.; 

 also in the collection of the author. 



POLYPLUMULARIA G. O. Sars (modified). 



rotypliimularia G. O. SARS, Forhandl. Vidensk. Selsk., I, Christiauia, 1873, p. 13. 



Trophosome. Colony pinnately branching, fascicled ; some of the hydrocladia furnished with a 

 hydrothecate ramulus which springs from the first iuternode and is more slender than the hydro- 

 cladium from which it grows. A single pair of supracalyciue nematophores. 



GonoKome. Gonangia sac-shaped, borne either on the fascicled branches or on the hydrocladia 

 near the origin of the accessory ramulus. 



Professor Allmau, in his report on the Porcupine Ilydroids, 1873, described a new species for 

 which he instituted the genus niplopteron, characterized by the doubly pinnate hydrocaulus and 

 two pairs of lateral uematophores. In the description of the type species, D. insigne, Professor 

 Allman mentions the accessory ramulus of the hydrocladia, but does not seem to regard it as a 

 feature of much importance. A few mouths before the publication of Professor Allman's report an 

 article appeared by G. O. Sars 1 , in which he described the genus r<tlyplminil(n-ia, based on the 

 presence of the accessory ramulus, which does not appear from his description to be constant. In 

 1S83 Allman 2 considers the two names Poly]>lumu laria and Diplopteron as practically synonymous, 

 the former having the priority. The present writer considers it best to retain both genera in modi- 

 fied form, including in Polypi it iiutlat-ia those species having the accessory ramulus, a pinnately 

 branching stem, and one pair of lateral uematophores. The distinction between this genus thus 

 modified and Schizotriclm, as defined in this work, is that in the former an accessory ramulus is 

 borne on ibepro.rimul intrntmle of the hydrocladium, while in the latter there is a bifurcation of 

 the hydrocladium beyond the first internode. 



POLYPLUMULARIA ARMATA, new species. 

 (Plate XVI, tigs. 5,6.) 



Trophosome. Colony attaining a height of 4 inches in an incomplete specimen, pinnately 

 branching, the alternate branches giving forth alternate branchlets from which the hydrocladia 



1 Bidrag til Kundskaben om Norges Hydroida, Videnskabernes Selskab8 Forhaiidhnger for 1873, p. 13, Clmsti- 

 ania. 



Challenyer Report, Hydroida, Pt. 1, p. 30. 



