4 Rev. T. Hincks on the 



M. compacta bears a very close resemblance in the details of 

 its structure, and with which it is probably identical, though 

 the Californian form has more cells in the internode, and is 

 furnished with a more fully developed operculum. A dis- 

 tinctive feature of the species is the position of the operculum, 

 very close to the lower extremity of the area. 



SCRUPOCELLARIA, Van Beneden. 



Scrupocellaria varians^ n. sp. (PI. XIX. figs. 1-1 c.) 



Zoarium much branched dichotomotisly, forming a shrubby 

 tuft. Zooecia biserial, alternate, elongate, enlarged above, 

 tapering off downwards ; area about half, or sometimes more 

 than half, the length of the cell, oval, margin thin and smooth, 

 three spines on the outer side above and one on the inner ; 

 the portion of the cell below the area tapering, smooth ; oper- 

 culum small, usually trifid. Lateral avicularium either small 

 and of normal shape (mandible pointed), or more commonly 

 much elongated upwards, in the direction of the line of zooecia, 

 extending a considerable way above the top of the cell to 

 which it is attached, consisting of a long channelled beak (free 

 through a great part of its length), terminating above in two 

 spinous points, and a slender setiform mandible, bent at the 

 apex, with an expanded triangular base, which, when at rest, 

 falls into the groove traversing the beak ; usually at the 

 bottom of the area a prominent sessile avicularium with pointed 

 mandible. Vibracular cell wedge-shaped, the terminal groove 

 stretching transversely across the back of the cell ; seta rather 

 long and very slender. Ooecium subglobular, smooth and 

 shining. 



Height of the tuft ^ an inch. 



Log. Off Cumshewa Harbour, growing on shell. 



The remarkable point in the present species is the curious 

 modification of the lateral avicularium. In form and struc- 

 ture the avicularian appendages are, as a rule, more constant 

 in this and the kindred genera than in most other sections of 

 the Polyzoa. I know of no deviation from the ordinary type 

 except in the present case and in a species (which I hope 

 shortly to describe) which is furnished with an elongate, sub- 

 spatulate avicularium, very unlike the normal form of the 

 appendage in this tribe. 



In 8. varians both the ordinary and the modified form of 

 the avicularium occur on the same specimens ; the two are 

 intermingled, but the latter is much the more abundant. I 

 venture to think that we have here additional evidence of a 



