a Si/stem of tht Calcareous Sponges. 185 



Genus 26. Leuconia, Grant. 



Gen. char. Persons of the stock united by the greater part 

 of their body-wall ; only their stomachal cavities and mouth- 

 openings separated. Mouth-openings simple, without pro- 

 boscis or peristomial crown. Five species. 



102. L. niveaj Bb. (>S^. ntvea, Grant). British coasts. 



103. L. Gossei, O.S. {Leucogypsia Oossei^Wo.). Channel 



Islands. 



104. L. stilifera^ O. S. Greenland. 



105. L. algoensisj H. {Leiicogypsia algoensis, Bb.). Algoa 



106. L. solida, O. S. {Grantia sohda, var. sociahs, O. S.). 

 Dalmatia (O. S.). 



Order III. CffiNOSYCA, H. 



Character. The mature calcareous ftjyonge forms a coenohium 

 (a stock composed of several persons with a single common 

 mouth-opening). Body branched, with its branches every- 

 where coalescent and anastomosing, and finally running to- 

 gether into a single mouth-opening. (Rarely the persons also 

 grow together externally to form a massy lump, as in Cceno- 

 storaeUa.) 



Family IX. Nardopsida, H. 



Character. The mature calcareous sponge forms a stock 

 with a single mouth-opening, the canal-walls of which are 

 only traversed by simple cutaneous pores (as in the Olynthida 

 and Soleniscida). 



Genus 27. Nardoa, O. S. 



Gen. char. Mouth-opening simple, not produced into a 

 thinly membranous proboscis. Two species. 



107. N. guancha^ H. {Guancha hlanca, var. C, M.-M.). 



Lanzarote, (M.-M.). 



108. N. lacunosa, O. S. {Grantia lacunosa, J.). British 

 coasts. 



Genus 28. *Naedopsis, nov. gen. 



Gen. char. Mouth-opening produced into a long thinly 

 membranous proboscis. Two species. 



109. *i\r. gracilis^ H. Australia. 



110. N. reticulum^ O. S. {Nardoa reticulum^ 0. S.). Dal- 



matia, O. S.) 



Ann. (Si Mag. N. Hist. Ser. 4. Vol.\. 13 



