REPORT ON THE HYDROIDA. 51 



gouaiigia are borne on the brandies of the phylactocarp instead of being carried at its 

 base by the stem. From Cladocarpus ventricosus it further differs in the cylindrical 

 instead of ventricose form of the hydrotheca. 



The pectination of the branches of the phylactocarp is due to the presence of 

 nematophores, which are disjjosed in two opposite series from the base to the summit of 

 the Ijranch, and which, instead of remaining in the usual condition of small sessile cups, 

 have become developed into long cylindrical tubes. In Cladocarpus dolichothcca and 

 Cladocarpus ventricosus, the nematophores, which are also present on the branches of the 

 phylactocarp, are disposed in a single series, and retain their normal form. 



The hydrocladial internodes of Cladocarpus pcctinifcrus are provided with numerous 

 transverse intra-cauline ridges, situated at equal distances from one another. Owing to 

 the transparency of the chitinous periderm, these are very distinct, and give to the 

 internode the appearance of being divided into distinct chambers by regular septa — a 

 character which is very obvious and striking. 



The hydrotheca of the internode, from which the phylactocarp springs, is destitute of 

 mesial nematophore, and the phylactocarp springs not exactly from the mesial line of the 

 internode, but from a point a little to the side of this, just IjcIoav the hydrotheca. The 

 absence of a mesial nematophore, in its normal form, is here not without significance, and 

 affords grounds for believing that the phylactocarp, notwithstanding its slight displace- 

 ment, is its homological representative. 



Cauline nematophores are borne in a single scries along the front of the stem, and give 

 to its lower end, where this is destitute of pinua% an appearance easily comparable to that 

 of some of the single-sided graptolites. Like most deep-water species, Cladocarpus 

 pectiniferus is distinguished by the delicacy and transparency of its chitinous periderm. 



Dredged at Station 7(3, July 3, 1873, lat. 38° 11' N., long. 27° 9' W. ; depth, 900 

 fathoms; bottom temperature, 4°"2 C. ; bottom, globigeriua ooze. 



CladocarpiLS formosus, AUm. (PL XVI. figs. 4, 5). 



Cladocai'ims formosn-s, AUman, Trans. Zool. Soc. Loud., vol viii., 1873. 



TropKosome. — Colony attaining a height of about four inches ; stem simple or very 

 sparingly branched, fascicled below, becoming monosiphonic distally, springing from a 

 tuft of delicate tubular filaments ; hydi'ocladia alternate, attaining a length of about one 

 inch. Hydrotheca^ cylindrical, with crenate margin ; mesial nematophore divided by an 

 imperfect transverse septum into a proximal and a distal half, aduate for somewhat more 

 than half its length to the hydrotheca, then becoming free, attaining the level of about 

 half the height of the hydrotheca, and opening by a wide terminal emarginate orifice ; 

 lateral nematophores short, cup-shaped, very slightly overtopping the h5'drotheca. 



Gonosome. — Phylactocarp in the form of a slender branch, which springs from the 



