THE PLUJIULAKID.E. f>7 



springs from au iuternode it is borne on ;i process from the proximal part of that internode, a nil 

 where there are two hydrocladia to a single internode they spring from the proximal and distal 

 ends of that interuode; there is a hydrotheca borne on each process at its junction with the stem; 

 hydrocladia alternate, borne on the main stem and its branches and divided irregularly into inter- 

 nodes which bear one or two hydrotheca^ each ; where there is a single hydrotheca to au internode it 

 is borne near the middle of that internode, but where there are two hydrotheca' to au internode they 

 are borne on the ends of that interuode. Hydrothecu' deep, cylindrical, almost twice as deep as 

 wide, margin circular aud even, very slightly everted; the hydrotheca' borne on the hydrocladial 

 processes at their .junction with the stem are shorter than the others; lateral uematophores borne 

 on very slight processes of the iuternode, just below the top of the hydrotheciu; a mesial neniato- 

 phore between adjacent hydrotheca', often two on the proximal internode of the hydrocladiuui 

 and an apparently irregular number ou the main stem aud its branches. 



Gonosome. (louangia ovate, with a circular aperture and containing a number of developing 

 ova. They are borne on the hydrocladia at the bases of the hydrotheca' aud are each provided 

 with a pair of nematophorcs. 



Distribution. Albatross Station 2415, lat. X. 30 44'. long. W. 79 2(i'. 440 fathoms; Albatross 

 Station 2667, lat. N. 30 53', long. W. 79 42' 30", 273 fathoms. 



This interesting form is so different from the other species of Plumularia that it may eventually 

 be found worthy of a new genus. The structure of the stem appears to be very similar to that 

 found in the family Perisiphonida- of Allman; the hydrotheca' on the stem at the axils of the 

 hydrocladia show its affinity with the catharina group of Plumularia, while the shape of the 

 hydrotheca- reminds one forcibly of P. cylindrica Kirchenpauer. 



Type slides. Vat. Xos. 18G11, 18612, U.S.N.M. ; Cat. Nos. 11719, 11720, Mus. State Univ. Iowa; 

 also in collection of the author. 



PLUMULARIA DENDRITICA, new species. 

 (Plate VIII, tigs. 4-6. ) 



Trophosoine. Colony attaining a height of 18 inches, profusely branching in au arborescent 

 manner, there being branches of at least six different ranks. The main stem branches in an 

 irregular manner and these branches divide several times irregularly until the hydrocladia-bearing 

 branches are reached, when the branches assume a pinnate form; stem fascicled, the central tube 

 being divided into irregular but usually very long interuodes, each of which normally bears several 

 hydrocladia on processes from the sides of the tube; these processes also bear a small projection 

 such as Dr. Fewkes calls a nematophore in P. caulitheca; the nodal joints become less frequent 

 toward the distal ends of the branches; there are no hydrotheca' on the stem or any of the 

 branches except the liydrochulia; hydrocladia alternate, divided into rather long regular hydro- 

 thecate internodes, with au occasional very short intermediate iuternode, the nodes being frequently 

 associated with one or two internal thickened ridges which simulate nodal joints and give the 

 appearance of several very short internodes. Hydrotheca' closely approximated, very small, deep, 

 about twice as deep as wide, margin sinuous in front aud obliquely cut away at the postero-lateral 

 corners, aperture slightly less than the greatest diameter of the hydrotheca; supracalyciue 

 uematophores borne ou very small projections just above and inside of the top of the hydrotheca;, 

 and usually pendant within the cavity of the latter; a single mesial nematophore is borne on a 

 stout process below the base of each hydrotheca, a cauline nematophore is found at the axil of 

 each hydrocladium, and several on each internode of the stem. 



Gonosome. Xot known. 



IHxtribution. Near Little Cat Island, Bahamas, shallow water, State University of Iowa 

 Expedition. 



Type slides. Cat. Nos. 11717, 11718, Mus. State Univ. Iowa; Cat. Nos. 18613, 18614, U.S.N.M.; 

 also in the collection of the author. 



This is probably the bulkiest species of Plumularian hydroid yet discovered in American 

 waters. The stem in one of our specimens is over half an iuch in diameter and greatly resembles 

 a gorgonian stem. 



