I 
2 THE VOYAGE OF H.M.S. CHALLENGER. 
Stylactis vermicola?- n. sp. (PI. I. figs. 2, 2a). 
Trophosome. — Hydranths clavate, with a circlet of about eight tentacles, and with 
their rudimentary stems springing at short intervals from a creeping, loosely branched, 
stolon-like hydrorhiza which is destitute of spine-like appendages. 
Gonosome. — Gonophores oviform, shortly pedunculate, springing from the hydranth 
close to its proximal end, or from the hydrorhiza. 
Locality . — Station 244, North Pacific; lat. 35° 22' N., long. 169° 53' E.; depth, 
2900 fathoms. 
Stylactis vermicola derives special interest from its singular habitat as well as from 
the great depth at which it was found living. Professor M c Intosh, while engaged with 
his Report on the Annelids collected by the Challenger, found that a colony of Hydroids 
had attached itself to the back of a specimen of Lsetmonice producta, an Aphrodita-hke 
Annelid obtained by the trawl in the North Pacific, from a depth of 2900 fathoms. The 
Hydroid lay entirely under cover of the scales, which are disposed in two imbricated 
series over the back of this Annelid, and an examination of a specimen sent to me by 
Professor MTntosh has shown it to be an undescribed species of Stylactis. 
The hydrorhizal stolon crept over the back of the Annelid and was crowded with 
thick, club-shaped hydranths of various sizes and in various stages of contraction. From 
the creeping stolon numerous very short tubular offsets were emitted. These formed so 
many rudimental stems which were invested like the hydrorhiza with a perisarc, while 
each supported on its summit a claviform hydranth, with about eight filiform tentacles 
disposed in a single circlet round the base of a thick conical hypostome. 
Some of the hydranths gave support to gonophores which were carried on very short 
peduncles close to the proximal end of the hydranth, while similar short-peduncled 
gonophores were also borne by the hydrorhiza close to the base of a hydranth. No 
difference either in form or size could be seen between those hydranths which carried 
gonophores and those which were without them. 
Family EUDENDRIDiE. 
Character of the Family. Trophosome. — Hydranths with trumpet-shaped hypo- 
stome, tentacles filiform in a single verticil. 
Gonosome. — Gonophores hedrioblastic. 
1 It is to this species that allusion has been made in the Narrative of the Cruise (vol. i. part ii. p. 753), where it is 
spoken of as referable to a new Calyptoblastic genus. More mature consideration has led me to believe that it has no 
characters which would justify its separation from Stylactis , the generic group in which it is here included. 
