216 Rev. T. Hincks on the 



Tlie cells of this species bear a strong general resemblance 

 to those of the genus Brettia, but the articulated avicularium 

 is a link connecting it with Bugula. Its place, I think, is 

 in the Bicellarian series. At the same time it possesses cha- 

 racters which probably entitle it to generic rank. Too much 

 importance must not be attached to the uniserial habit ; but 

 the small aperture, so unlike that of the true Bugulce, and tlie 

 tubular prolongation of the cell below are structural features 

 of considerable moment. In the form and position of the 

 avicularia this species agrees with Bugula. The genus Bugu- 

 lella, instituted by Verrill for a species which he obtained on 

 the coast of North America, seems, so far as we can judge in 

 the absence of a figure and specimens, to be founded on a 

 different type. 



Family CellulariidsB. 

 Cellulaeia, Pallas. 



CeUuJaria Peacldi^ Busk. (PI. XV. fig. 6.) 



I have figured this well-known species from a St.-Lawrence 

 specimen to show the cusp on the median cell at the bifurca- 

 tion of the branches, which it sliares with the Australian G. 

 cusiridata of Busk. It is true that it is frequently absent (in 

 both species I believe), but there is no doubt that it occurs in 

 the North- European as well as the Australian species, and is 

 not by any means a distinctive character *. 



Family CribrilinidsB, Hincks. 

 Membkaniporella, Smitt (part.). 



Membraniporella crassicosta, n. sp. (PI. XIV. figs. 5.) 



Zocecia ovate, disposed (rather irregularly) in lines ; front 

 wall composed of a few (about six or seven) broad, flat, and 

 rather massive ribs, usually more or less separated by con- 

 siderable interspaces ; no distinct sternum ; orifice (secondary) 

 suborbicular, enclosed by two stout rib-like processes which 

 unite in front ; oral spines wanting. Avicularia none. 

 Ooecium (?). 



Hah. Spreads in reddish-brown patches over various kinds 

 of Polyzoa {Escharoides Sarsii &c.) . 



The species to which the present form makes the nearest 



* See Busk's ' Challenger ' Report, part 1, p. 17. Mr. Busk suggests 

 the propriety of recurriug to bis original name, Cellularia monotrypay in 

 place of C, cvspidata, if the presence of the cuspidate poiut should prove 

 to be also a character of C, Peachii. 



