44 CELLULARIID.fi. 



racter of Scrupocellaria, and that which gives it its distin- 

 guishing fades, is the association of a lateral aviculariura 

 and a dorsal vibraculum on each cell. The position of 

 these appendages is very constant; and though one or the 

 other may be occasionally absent, they are generally to be 

 met with on most of the cells in a colony. They vary 

 much, under differing circumstances, in the degree in 

 which they are developed. The lateral avicularium, which 

 is sometimes almost gigantic, is occasionally so much 

 atrophied as to be hardly distinguishable. The cause of 

 the reduced condition in such cases may be found in the 

 size and number of the avicularia on the front of the cell, 

 which have superseded it by discharging its functions. 

 The vibracula also are sometimes much below the normal 

 size, but seem to be less liable to variation than the avicu- 

 laria. In one species from the Gulf of St. Lawrence and 

 also (I believe) from the Mediterranean, the vibracular 

 cell is unusually large, stretching completely across the 

 back of the zooecium to the median line, and traversed 

 throughout by the groove or fissure, in which the vibra- 

 culum itself rests. This form makes an approach to 

 Caberea. 



The habit of the Scrupocellaria is erect, and their mode 

 of growth regular and somewhat stiff. The internodes 

 are long, and the corneous joints but slightly developed. 

 They want the graceful curled extremities of the Menipeee ; 

 and the prehensile appendages of the latter are supplanted 

 by modifications of the fibrils, which act chiefly as organs 

 for fixing the zoarium in its place. Instead of tendrils 

 and claspers we have grapnels. 



The Scrupocellaria form a rather large group, and are 

 widely distributed. S. scruposa, which is so common in 

 the seas of Europe, ranges from Norway to New Zea- 

 land. The genus is represented sparingly in the Arctic seas 



