196 



Family Setosellidae ' n. 1'. 

 Setosella Hincks. 



The zoii'cia the frontal wall of which is perforated by two slit-shaped opes- 

 iulae have a well chitinized simple oporculuiii with a well developed opercular 

 arch. No spines. The lateral walls which are comnion to the contiguous zoci'cia 

 are in their distal jjart provided with a large membranous, uniporousC?) rosette- 

 plate. Obliquely, distally to each zooecium is found an independent i>il>r(iciiliim 

 without a cross-bar, with a long, strong, dentate flabelluni. The ocrcia are small 

 rounded cavities in the frontal wall of the arched distal part of the gonozoa'cium, 

 the 'ooccial areas which is distinctly separated from the lateral jiarts by an 

 impressed line. The ooecial cavity which is distinctly apparent on the outer sur- 

 face opens out through a hole gradually increasing in size. 



The Goecia of the present genus, which have hitherto been overlooked, belong 

 to the same division of ooecia (p. 65), the endotnichal, found in the genera Cellii- 

 laria and Membranicellaria, but while in these they are placed in the proximal 

 pari of the frontal wall, they are in Setosella placed in the distal part of this 

 wall. 



While the aperture of the common zoa-cia is about as high as broad the 

 aperture of the gonozoa'cia is broader than high, with a somewhat convex proxi- 

 mal margin and with two acuminated corners. 



On account of the ooecial form I have thought il necessary to set up a new 

 family for this genus which is represented by a single s[)ecies i". viilnerala IJusk. 

 Of this species colonies have been taken by the Ingolf Expedition at Lat. 25" 21' N., 

 Long. 63" 21' W., at a depth of 170 fathoms. 



Family Chlidoniidae. 



The jointed colonies, springing from a stolonate network, consist of a stem, 

 two main branches and a number of zocccia-bearing secondary branches, and 

 besides the zocecia we may distinguish between three different forms of kenozooecia, 

 namely the partitions of the stolon, the stem-internodes and the bifurcate inter- 

 nodes of the main branches. Moreover, the main branches and the secondary 

 branches end in a number of small cylindrical internodes, of which those in the 

 •secondary branches may be transformed into zooecia. The zooecia, which lack 

 pores and spines, have a deejjly depressed cryptocyst, pierced by a small trans- 



' Neither this family nor tlie family Crepidacantbidae arc naimd in the synopsis on p. 88, both 

 families having been founded later. 



