180 M. E. Hackel's Prodromus of 



perigastric radial chambers, which surround the stomach in 

 the same way as in the corals, are probably produced by the 

 deficiency of the horizontal partitions which, in Sycariunij 

 Sycum^ &c., separate the superposed radial canals. Each 

 perigastric chamber opens by a longitudinal series of stoma- 

 chal pores into the stomachal cavity, and outwardly by several 

 longitudinal rows of cutaneous pores.) Mouth-opening sim- 

 ple, without either proboscis or peristomial crown. One 

 species. 



52. *C. actinia^ H. Honolulu (Haltermann). 



Family IV, Dyssycida, H. 



Character. The mature calcareous sponge forms a simple 

 sac-like person furnished with a single mouth-opening, and the 

 stomachal wall of which is traversed by irregular ramified 

 canals (parietal canals). (The parietal canals communicate 

 repeatedly with each other, and open at the proximal end into 

 the stomach by a few large stomachal pores, and at the distal 

 end, outwardly, by very numerous small cutaneous pores.) 



Genus 13. *Dyssycum, nov. gen. 



Gen. char. Skeleton consisting of triradiate spicules in the 

 body-wall, of quadriradiate spicules, the fourth ray of which 

 projects freely into the stomachal cavity in the stomachal wall, 

 and of simple, freely projecting spicules at the surface of the 

 body. Mouth-opening simple, without either proboscis or 

 peristomial crown. Five species. 



53. D.fistulosum,a.{Granttafstulosa,J.). British coasts. 



54. D. pemcilJatum, H. {Sycinula penicillata^ O. S.). 



Greenland. 



bb. D. clavigerum^ H. [Sycinula clavigera^ 0. S.). Green- 

 land (0. S.). 



bQ. D. soliduni, H, [Grantia solida^ var. solitaria^ O. S.). 

 Dalmatia (0. S.). 



57. '''D. periminum^ H. Perim, Red Sea (Siemens). 



Genus 14. *Dyssyconella, nov. gen. 



Gen. char. Skeleton as in Dyssycum. Mouth-opening pro- 

 duced into a proboscis (a thinly membranous tube not tra- 

 versed by parietal canals), without a peristomial crown. Two 

 species. 



58. D. pumila, H. [Leuconia pumila, Bb.). Guernsey 



(Norman). 



59. *D. caminns, H. Antilles. 



