144 CATALOGUE OF THE ZOOPHYTES OF 



On tlie under side of stones between tide-marks ; frequent. 

 More rarely in shallow water. 

 This species was described by Dr. Johnston, under the above 

 name, in the Transactions of the Newcastle Natural History 

 Society, but he afterwards united it with the Flustra lineata in 

 his " British Zoophytes." It appears, however, to have well 

 marked distinguishing characters. It spreads over stones in 

 yellowish brown, coriaceous or slightly calcareous patches, of 

 iiTCgular outline and thickly set with spines. Old specimens 

 are often a good deal obscured by grains of sand, or other ex- 

 traneous substances. The cells are closely set, and more elon- 

 gated than in M. lineata, and the spines, which are frequently 

 opaque, are stouter and more numerous. But what more par- 

 ticularly distinguishes M. spinifera is that some of the spines 

 bear an avicularium near the top. Such spines are more or less 

 broadly clavate or fusiform, with a pointed apex, below which, 

 on one side, is the avicularium, with a mandible opening down- 

 wards; sometimes it is on the extreme apex. This peculiarity 

 appears to have hitherto escaped notice. The avicularia are 

 rather rare, but may generally be detected on some part of a 

 specimen that has not been injured. They adhere less closely 

 than the other spines, and are more readily rubbed off. The 

 ovicapsules are seldom developed, and when present are so 

 inconspicuous as to be with difficulty recognised. They appear 

 to be smooth and very shallow, with a rib across the front, and 

 two or more spines on the top. 



5. M. cRATicuLA, n. sp. PI. X., fig. 3, 3a. 



Cells in linear series, small, oval; the margin with 5 to 

 7 spines on each side, which are shining, flattish at 

 the edges, and lie closely over the aperture ; one or two 

 of the uppermost spines are erect, long, and cylindrical. 

 Ovicapsule rather small, smooth, and cylindrico-globose, 

 with a rib across the middle. An avicularium generally 

 at the top of the ovicapsule, sometimes at its side. 



Flustra lineata^ Couch, Corn. Fauna, part 3, p. 124, 

 t. xxii., f. 15? 

 On Modiolce from deep water; occasionally. 



