APPENDIX. 367 



farciminoides in the younger cells, and which opening is 

 probably normal, until it becomes filled up by the gradual 

 deposition of calcareous matter. What more especially 

 distinguishes the present from the preceding species are 

 the minute projections on either side at the two upper 

 lateral angles of the hexagonal area, and the smoothness 

 of the surface of the cell. They are both perfectly distinct 

 from S. farciminoides. 



b. Sm-face not divided into distinct areas by raised 

 ridges. 



3. S. dichotoma. n. sp. 



Mouth of cell elliptical, occupying two-thirds of its 

 length. Two small perforations on each side immediately 

 above the mouth, protected by a convex transparent hood, 

 which has a rounded opening on its under suiface. 



Hab. — Prince of Wales Channel^ Torres Strait, nine 

 fathoms. 



Forms small crowded tufts from one to two or thi'ce 

 inches high ; branches very regularly dichotomous. 



4. S. marginata. n. sp. 



Cell circumscribed by an acute raised border ; opening 

 oval, rather more than half the length of the cell. Cell 

 attenuated below the opening. 



Hab.— Prince of Wales Channel, Torres Strait, nine 



fathoms. 



A small broken fragment only preserved ; parasitic upon 

 Sertidaria inutulata, so that its habit cannot be satis- 

 factorily determined. It is of a greenish colour, but tliis 

 may be adventitious, although general and uniform 

 throughout the specimen. This species differs fi'om the 

 above in being much larger, and in wanting the two per- 

 forations on each side above the mouth— in the less 

 comparative size of the opening of the cell, and in the 



