REPORT ON THE HYDROIDA. 25 



therefore, no other difference of greater importance exists, I believe it will be best to 

 follow the earlier systematists, and combine all such forms under a single genus, of which 

 the well-known Antennularia antennina may be taken as the tyj^e. 



The hydi'ocladia of Antennularia fascicularis spring from the outer tubes of the 

 polysiphonic stem, each hydrocladium being supported on a short process from the 

 tube, and having at its proximal end two short internodes followed by a long one, all 

 three destitute of hydrothecse. In the deep hydrothecas, Antennularia fascicularis 

 further contrasts with the tyT^ic?! AntennularicB, whose small shallow hydrothecse are, as a 

 rule, characteristic of the genus ; while the position of the gonangia on the hydrothecal 

 internodes, instead of being borne in the axils of the hydrocladia, affords another 

 distinctive feature. 



The proximal end of the specimen in the collection had been broken off, so that 

 nothing can be asserted with exactness regarding the height attainable by the colony or 

 the characters of the hydrorhiza. 



Antennularia fascicularis is wanting in the graceful habit by which most of the 

 Plumularidae are characterised, the thick strongly fascicled stem, and the irregularity of 

 the fine hair-like ramuli, giving it a somewhat inelegant habit, which contrasts with 

 the lightness and grace of most other species. 



Dredged off Nightingale Island, Tristan d'Acunha, from a depth of 100-150 fathoms. 



Sciurella, nov. gen. 



Name, a dimmutive noun fornieil from Sciurus, a squirrel, in allusion to the squirrel-tail-like 

 disposition of the hydrocladia. 



Genekic Character. Trophosome. — Hydrocladia not disposed in pinnae, but spring- 

 ing from many points round the circumference of chord-like stems. 



Gonosome. — Gonangia situated in the axils of the hydrocladia, provided with sym- 

 metrically disposed horn-like processes, and enclosing a ramified blastostyle, whose 

 branches are in connection with moveable nematophores distributed over the surface of 

 the gonangium. 



The species on which the genus Sciurella has been founded has the general aspect of 

 Antennularia antennina. From this, however, it differs not only in the disposition of 

 the hydrotheca-bearing ramuli, but in the much more important character presented by 

 the remarkable gonangia with their ramified blastostyle, their horn-like p)rocesses, and the 

 nematophores carried on their walls. These nematophores belong to the ordinary 

 moveable type, and communicate through perforations in the walls of the gonangium 

 with the prolongations of the ramified blastostyle. 



(ZOOL. CHALL. EXP. PART XX. — 1883.) U 4 



