474 PEOFESSOE G. J. ALLMAJf ON THE HTDROIDA 



SERTULAEID^. 



DiPHASIA COEONIFERA. Plate LXVI. figs. 2, 2". 



Trojihosome. — Stem attaining a height of about three inches, simple (in specimen), 

 stout, rigid, not fascicled, tapering towards the summit, pinnate ; pinnae alternate. 

 Ilydrothecae tubular, with the margin entire, free for about the upper third, which 

 diverges without any abrupt bending from the axis, each pair of hydrothecse on the 

 pinnae separated from its neighbouring pairs by an interval of about half the length of 

 the hydrotheca, but by about double that interval on the main stem. 



Gonosome. — Gonangia (male) springing from the pinnae, each at a point just below 

 a hydrotheca, contracted below into a short curved peduncle, rapidly expanding upwards, 

 and terminating in a broad circular summit, whose circumference is raised into eight 

 similar, strong, broad spines, and from whose centre projects a short papilliform process 

 carrying the orifice on its extremity. Female gonangia not known. 



This species was dredged in lat. 64° 15', long. 6° 15', from a depth of 632 fathoms. 



Sertulakella Gati, var. robusta. Plate LXVI. figs. 3, 3". 



The form here recorded as a variety of Sertularella Gayi is a Hydroid with a strongly 

 fascicled, thick, rigid stem, which attains a height of about six inches, and sends ofi' on 

 all sides simple, non-fascicled, obliquely jointed ramuli, and occasionally a fascicled 

 branch, from which non-fascicled ramuli then proceed, as in the main stem. The 

 hydrothecse are borne one on each intemode of the ramuli, immediately below a joint ; 

 they arch outwards from the ramulus, are turgid below, marked upon the upper side by 

 transverse rugae, smooth below, and have an obscurely four-toothed aperture. 



The gonangia (female X) are ovate, on short peduncles, strongly annulated towards the 

 summit, but smooth below ; the summit is in the form of a saucer-shaped expansion, 

 from the centre of which rises a conical process, carrying on its top an obscurely two- 

 lobed orifice. 



If it were not for the occurrence of intermediate forms, I should have regarded the 

 present Hydroid as specifically distinct from Sertularella Qayi. It differs from typical 

 specimens of *S^. Gayi by the irregular disposition of its ramuli (which in the latter 

 species are pinnate), and by the tubular summit of the gonangia. From S. j)olyzonias, 

 with which S. Gayi is closely allied, it difi'ers by its much more robust habit and thick 

 fascicled stems. In specimens obtained from some other dredgings of the ' Porcupine,' 

 the ramification is rather more pinnate. It seems, indeed, to form a connecting link 

 between S. j)olyzonias and S. Gayi, and would thus go far to justify us in regarding all 

 three as merely varieties of a single species. 



The form here described would seem to be rather widely distributed over the area 

 explored. It was obtained from the cold region, at depths of 345, 363, and 605 fathoms, 

 with a bottom-temperature which varied from 31°'4 Fahr. to 29°'8 Fahr., while it was 



