99 SERTULARELLA GAYT. 
Sertularella amphorifera. 
Pl. XV. Figs. 8-10. 
Trophosome. — Hydrocaulus very slender, dichotomously branched ; inter- 
nodes long, attenuated, each carrying a hydrotheca near its distal end. Hy- 
drothece nearly cylindrical, deep, adnate to the internode for about their 
proximal third, then becoming free and bending outwards; margin with 
three teeth, one internal and two lateral. 
Gonosome. —Gonangia springing each from a point near the base of a 
hydrotheca ; obovate, strongly annulated, rapidly narrowing to its point of 
attachment, and terminating distally in a conical neck, which carries on its 
summit a small cireular orifice with everted margin. 
Dredged off Double-Headed Shot Key from a depth of 471 fathoms. 
Sertularella amphorifera is very-closely allied to the S. tricuspidata of Alder. 
It is destitute, however, of the two or three oblique annulations which at 
intervals give to the stem in S. ¢ricuspidata a twisted appearance, while 
the disposition of the teeth of the hydrotheca is also different, there being 
an anterior but no posterior tooth in Alder’s species. Further, the gonangia 
of the present species become much more rapidly narrow towards their 
point of attachment, a condition which makes them closely resemble in 
form the old Roman amphora. 
The specimens in the collection were mere fragments, so that the full size 
to which the species grows could not be ascertamed. They were obtained 
from the deepest dredgings of the exploration 
Sertularella Gayi var. RoBusTA. 
Pl. XV. Figs. 3-5. 
I have assigned to the well-known species Sertularella Gayi the -hydroid 
here figured, which I regard as one of the many variations of that species, 
from the typical form of which it differs in its more irregular ramification 
and stouter habit. The specimens examined had attained a height of two 
or three inches, and sprung from a hydrorhiza composed of a dense tow- 
like mass of fine tubular filaments, formed by the disunion, free exten- 
sion, and repeated division of the tubes which constitute the fascicled stem. 
The valvular apparatus by which the orifice of the hydrotheca is closed 
was well seen in some of the specimens, and the four bands by which the 
valves are connected with the body of the hydranth were in some cases 
visible (Fig. 4). 
