of the National Antarctic E.cpedit'ion. 275 



but the first and tliird species are encrusting, and the second 

 has long slender branches. 



Dredged off Coulraan I., 100 fath. 



LiSSOMYXlLLA, llanitsch. 



Tliis genus, was establislied by Hanitscli * to include 

 Ectyonine Sponges with fibres having a core of siuootii 

 styles echinated by acanthostyles with special ectosoinal 

 niegascleres, and with or without rnicroscleres. Unfortunately 

 the species he selected as type of the genus {Tethea spi- 

 nosa, Bowerbank) in no way fell in with the definition, since, 

 as Topsent f points out, this species has neither echinating 

 spicules nor special ectosonuil spicules, and Topsent refers 

 Lissomyxilla to the limbo of useless names. Among the 

 * Discovery ' sponges, however, is a specimen which tits in 

 with Hanitsch's definition of Lissomy.cilla, which runs : — 

 " Skeleton fibres of the choanosome formed of smooth mon- 

 actinals echinated by spined styles. niegascleres of the 

 ectosome smooth diactinals or monactinals. Microscleres 

 (isochelae &c.) may be present." Accordingly I propose to 

 revive the name. 



Lissomyxilla IJanitschi, sp. n. 



There are two much-worn species of this sponge of a dark, 

 dirty-grey colour, and a third young small specimen, whitish 

 in colour, growing on a specimen of llornera. The largest 

 specimen is 4 cm. high and 5 cm. in diameter at the base ; 

 the dermal membrane is worn away, exposing several open- 

 ings of exhalant canals, 4 mm. in diameter. The dermal 

 nitnibrane of the smallest specimen is transparent, smooth, 

 and raised \\\) at one place into a small conical oscule, with 

 ladial tangential spicules in its walls. 



The sktleloti of the choanosome is formed of branching 

 fibres on an average about 150 fi thick, echinated by spined 

 styles in an obscurely verticillate manner, the whole skeleton, 

 as seen in sections, having a somewhat confused appearance. 

 The ectosonuil spicules partly proceed obliquely from the 

 main fibres to the dermal membrane, and partly lie tangenti- 

 ally in that membrane. 



Spicules. — Megascleres : styles, 500 x 10 /j,, smooth, curved 

 near the head, sharp-pointed. Echinating acanthostyles, 



* Trans. Livei-pool Biol. Soc. vol. viii. p. 194 (1894). 

 t Arcliiv. Zool. E.\p. et Gi5u. (-i) tome viii. p. -'05 (1900). 



