JREPORT ON THE TETRACTINELLIDA. 
cxxxix 
Genus 5. Stelletta (0. Schmidt). 
Stelletta, 0. Schmidt, Spong. Adriat. Meeres, p. 46, 1862. 
„ SoUas, Sci. Pioc. Eoy. Dubl. Soc., voL v. p. 192, 1886. 
Oscules distinct or not ; pores in sieves overlying completely differentiated chones. 
Cortex well developed, si mil ar in structure to that of Astrella. Of the two forms of 
aster which are present, one is generally distributed throughout the Sponge (somal), the 
other is restricted to the choanosome (choanosomal). 
Type — Stelletta boglicii, 0. Schmidt (p. 184). 
Genus 6. Dragmastra, Sollas. 
Dragmastra, Sollas, Sci. Proc. Eoy. Dubl. Soc., vol. v. p. 193, 1886. 
Sponge similar to Stelletta, but with the collenchymatous layer of the cortex crowded 
with orthodragmas. 
Tjrpe — Dragmastra normani, Sollas (p. 187). 
Genus 7. Aurora, n. gen. 
The cortex is not differentiated into two layers ; densely crowded with large spher- 
asters. 
Type — Aurora glohostellata (Carter) (p. 187). 
Subfamily 3. Sanidasterina. 
Genus 8. Ancorina (0. Schmidt). 
Ancorina, 0. Schmidt, Spong. Adriat. Meeres, p. 51, 1862. 
The cortex is thick and fibrous, and is not produced into tubular outgrowths. The 
sanidaster is confined to the ectosome ; in addition a somal chiaster or choanosomal 
oxyaster may be present. 
Type — Ancorina cerebrum, 0. Schmidt (p. 188). 
Genus 9. Tribrachium (Weltner emend. Sollas). 
TrihrcwJimm, Weltner, Beitrage z. Kenntniss der Spong., Inaug. Diss. Freiburg, p. 50, 1882. 
„ Sollas, Sci. Proc. Roy. Dubl. Soc., vol. v. p. 194, 1886. 
Sponge spherical, produced into a special cloacal tube, the megascleres of which are 
orthodisenes. The microscleres are sanidasters only, though a minute euaster may occa- 
sionally be present. 
Type — Tribrachium schmidtii, Weltner (p. 154). 
