198 Scientific Proceedings, Eoyal Dublin Society. 



daster, long hair-like rays, not numerous, 0-026 mm. in dia- 

 meter. 



Habitat— Station 122 ; of! Barre Grande. 350 fms. 



Synops nitidus, sp. n. — Sponge plate-like, horizontal, oscules 

 numerous, small, restricted to the upper surface over which they are 

 dispersed ; pores in sieves on the opposite surface ; cortex — beneath 

 the epithelium is a layer of small globo-stellates, this is succeeeded 

 immediately by the globate layer, which constitutes almost the 

 whole of the cortex. Spicules — (1) acerate 1*25 by 0*026 mm.; 



(2) fork, shaft, 1*07 by 0-039 mm., arms simple, 0*183 mm. long ; 



(3) ectaster, a globo-stellate, 00135 mm. in diameter; (4) endaster, 

 a small centrum, and long conical microspined rays, usually few 

 in number, - 044 in diameter. 



Habitat. — Port Jackson, Sydney. The smooth, shining, upper 

 surface is very characteristic, aud no other species of ^Synops presents 

 the same horizontally spreading form. 



Synops neptuni, sp. n. — This is the largest'tetractinellid sponge 

 known. It has the form of a somewhat conical cup with a large 

 central cavity, rising from a base of 12 cm. diameter to a height 

 of 40 cm. ; where broadest its diameters are 22 cm. and 31 cm. 

 Its wall is intricately folded. The oscules are confined to the 

 inner surface of this cup. 



Habitat. — Station 122 ; off Brazil. 32 fms. 



Isops pachydermata, sp. n. — Sponge, irregular, massive; surface 

 smooth ; oscules and pores singly perforating small rounded bosses ; 

 cortex thick, constituted almost entirely of the globate layer; 

 beneath the epithelium a layer of globo-stellates. Spicules — 

 (1) acerate, 1-96 by 0-052 mm. ; (2) fork, shaft, 1*07 by 0-039 mm. ; 

 arms simple, 0-27 mm. long ; (3) globate, a compressed ellipsoid, 

 0-24 by 0*19 mm. in diameter; (4) ectaster, a globo-stellate, 0-016 

 in diameter ; (5) endaster, centrum small, spines conical, sharply- 

 pointed, few ; single ray of a triad form, - 064 mm. long ; (6) a 

 stellate intermediate between (4) and (5). 



Habitat —Station 56 ; lat. 32° 8' 45" N. ; long. 64° 59' 35" W. 

 1075 fms 



