a General History of the Marine Polyzoa. 75 



the walls of great thickness, round the edge a conspicuous 

 row of punctures, often channelled ; orifice raised, with the 

 peristome somewhat thickened, arched above, almost straight 

 below, rather taller than broad, with about nine marginal 

 spines ; in the centre of the front wall, about one third the 

 length of the cell below the orifice, a large circular or ellip- 

 tical pore, often with a number of nodules about it, and 

 shielded on one side by a low calcareous ridge ; on the other 

 side a very large pointed avicularium, directed upwards, and 

 reaching to about the middle of the orifice; sometimes an 

 avicularium on each side. Ouicium very prominent, gibbous in 

 front, partially invested towards the base with one or more 

 layers of a dense whitish crust. 



hoc. Madeira, in 30 fathoms (J. Y. J.). 



Range in Time. Vienna basin (Reuss) ; Italian Pliocene 

 (Manzoni) . 



Lepralia decorata, Reuss, is a characteristic member of the 

 present genus, ranking alongside our British M. violacea. 

 It has hitherto only been known as a Tertiary fossil ; but 

 it seems, judging from the number of specimens amongst 

 Mr. Johnson's dredgings, to be far from uncommon at 

 Madeira, and is a very interesting addition to the recent 

 fauna. 



It is a very thick- walled species, and, in its older states, 

 presents a very coarse and rugged appearance, the surface 

 being covered with nodules and bosses or traversed by ridges. 

 In some cases the central pore is in great part surrounded by 

 a continuous wall. The punctures are sometimes diffused 

 over the whole surface ; often they are arranged concentrically 

 in two or more series. There is generally only a single avi- 

 cularium ; but cells frequently occur which are armed with two, 

 and in some specimens almost every cell has one on each side. 

 In young and fresh specimens the texture is delicate and the 

 surface glossy and of a greyish-white colour. 



As in M. violacea, there is often a striking diversity in the 

 size of the zocecia within the limits of the same colony. There 

 seem to be no differences of any moment between recent and 

 fossil examples ; Manzoni's figure of the species is very 

 characteristic. 



I am not in a position to give an exhaustive list of the 

 published species which rank under this genus (Microporella) . 

 The following are all that occur to me at present as belonging 

 to it : — the four British species, M. ciliata, Malusii, im- 

 pressa, and violacea, of which the first two have a very wide 

 range of distribution ; Lepralia calif'ornica, Busk, and L. 

 personata, id., both of which are probably vara, of .1/. ciliata ; 



