APPENDIX. 36S 



11. ScRUPOCELLARiA, Van Beneden. 



Char, (modified.) Cells rhomboidal^ with a sinuous 

 depression on the outer and posterior aspect. Each fur- 

 nished with a sessile avicularium at the upper and outer 

 angle in fronts and with a vihraculum placed in the sinus 

 on the outer and lower part of the cell hehind. Opening 

 oval, or subrotund, spinous above. Ovicells galeriform. 



This natural genus is characterized more particularly by 

 the presence upon each cell of a sessile avicularium seated 

 on, or in fact forming the upper and outer angle, and of a 

 vihraculum placed on the back of the cell. The cells in 

 some species are provided with a pedunculate operculum, 

 by which it is intended to designate a process, which arising 

 by a short tube from the anterior wall of the cell, imme- 

 diately beyond the inner margin of the opening, projects 

 forwards and bends over the front of the cell, expanding 

 into a variously formed limb, and serving as protection to 

 the mouth of the cell in front. The cavity of the tube by 

 which the process arises, becomes, in the expanded portion, 

 continuous with variously disposed grooves or channels, 

 which terminate at the edges of the operculum. This organ 

 affords excellent specific characters (not in this genus 

 alone). Besides the sessUe avicularia above noticed, many 

 species of this genus also possess avicularia of another kind, 

 and which are placed on the front of the cell below the 

 opening and towards the inner side, or in other words, to- 

 wards the middle hne of the branch. In this genus, in all 

 those species in which the second avicularium occurs, each 

 individual cell is provided with one. This additional avi- 

 cularium appears to be composed of a flexible material, and 

 it is very easily broken off, so that in many instances, per- 

 haps throughout an entire specimen the organ itself may 

 be wanting, although its position is clearly evidenced by 

 the existence of a rounded opening in the usual situation 

 of the organ. It is necessary to distinguish this form of 



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