22 SERTULARELLA GAYT. 



Sertularella amphorifera. 

 PI XV. Fi(/s. 8-10. 



Trophosome. — Hydrocaulus very slender, dichotoraously branched ; inter- 

 nodes long, attenuated, each carrying a liydrotheca near its distal end. Hy- 

 drothecse 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 circular orifice with everted margin. 



Dredged off Double- Headed Shot Key from a de)>th of 471 fathoms. 



Sertularella amphorifera is very closely allied to the S. tricuspidaia of Alder. 

 It is destitute, however, of the two or three oblique annulations which at 

 intervals give to the stem in S. tricuspidata 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 ascertained. They were obtained 

 from the deepest dredgings of the exploration 



Sertularella Gayi vnr. robusta. 

 PI. 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 n»any 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 coimected with the body of the hydranth were in some cases 

 visible (Fig. 4). 



