186 :M. E. Tliickers Prodromns of 



Family X. Ccenostomida, II. 



Character. The mature calcarcDus sponge forms a stock 

 with a single moutli-openin_i2:, the stomachal walls of which 

 arc traversed by irregularly brauchcil canals. 



Genus 29. *Ccexostomella, nov. gen. 



Gen. char. The persons of the stock arc united into a single 

 mass, the common mouth-opening of which is produced into a 

 thinly membranous ])roboscis, whilst the stomachal cavities of 

 the persons remain scj)aratcd. One species. 



Ill, *C cami)ius, H. Antilles. 



Order IV. CLISTOSYCA, H. 



Character. The mature calcareous sponge forms one person 

 ivithout a moxLth-opening . (The body usually appears under 

 the form of an ovate, spheroidal, or compressed bladder, the 

 internal cavity of which communicates with the surrounding 

 water only by cutaneous pores or ])arietal canals, but by no 

 large orifice (mouth) ; the mouth is closed up.) 



Family XI. Clistolynthida, H. 



Character. The mature calcareous sponge forms a person 

 without a mouth-opening, the wall of which is traversed by 

 simple cutaneous pores (as in the Olynthida). 



Genus 30. *Clistolynthus, nov. gen. 



Gen. char. Stomachal cavity simple, without partitions. 

 One species. 



112. *C. vesicula, H. Honolulu (Haltermann). 



Family XII. Sycocystida. 



Character. The mature calcareous sponge forms one person 

 without a mout]i-o])cning, the body-wall of which is traversed 

 by regular radial canals (radial tubes) as in the Sycarida. 



Genus 31. *SyC0C'YSTIS, nov. gen. 



Gen. char. Stomachal cavity quite simple, without com- 

 partments. Three species. 



113. */S. ovifornds, H. Heligoland (IL). 



114. *S. compressa, H. Norway. 



115. S. iitricuhts, 11. {Ute utr{cuhis,O.B.). Greenland. 



