180 ^I. E. Iliickel's Prodromns of 



perigastric radial chambers, which surround the stomach in 

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

 deficiency ot" the horizontid partitions which, in Si/cartunij 

 Si/cum, Sec, separate the superposed radial canals. Each 

 perigastric chamber opens by a longitudinal scries 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 pcristomial crown. One 

 species. 



52. *(7. 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 in-egular 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-Avall, of quadriradiate spicules, the fom-th 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.fstidosum, II. [Grantiajistulosa,S.). British coasts. 



54. D. peniciUatum, H. {Sycimda penicillata, O. S.). 



Greenland. 



55. D. clavigerum, H. [Sycimda clavigera, O. S.). Green- 



land (0. S.). 



56. D. solidinn, H. [Grantia solida, var. solitaria, 0. S.). 



Dalmatia (O. S.). 



57. *D. perimiman, 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. *Z>. caminv.i, H. Antilles. 



