General History of the Marine Polyzoa. 89 



and the front is enclosed by a raised line. I therefore no 

 longer identify these two. At the same time I am not pre- 

 pared to accept Mr. Waters's alternative without a more 

 careful examination of L. Poissonii than I am able to make 

 at present. Besides other differences, tlie lower margin is 

 represented in Savigny's figure as mucronate. If the Ma- 

 deiran form is ranked under Audouin's species, it must be as 

 a strongly marked variety. 



Heller's L, Kirchenpaueri Waters would refer to L. ad- 

 pressa. Busk. I confess I should be more inclined to recog- 

 nize it as a distinct species. The peculiar shape of the cell, 

 to which 1 have already referred, and the absence of vibracula 

 are good specific characters, which separate it from L. adpressa, 

 Busk ( = Z. lata, Busk). It is true tliat the latter is some- 

 times furnished with small nodular risings on each side a little 

 below the orifice *, but these never bear vibracula and have 

 no special significance. 



]bid. (p. 13 Sep.). 

 Mernbranipora albtda, sp. n. 



Tliis species is recorded doubtfully in the * Challenger ' 

 Report as occurring at two stations. Mr. Busk remarks that 

 the close resemblance between it and the ' Challenger ' speci- 

 mens " leaves little room for doubt as to their identity," the 

 cliief point of difference being the larger size of the avicularia 

 in the former. There is undoubtedly a great similarity 

 between the figures of the two forms. The position of the 

 avicularium is the same in both ; but there seem to be not 

 unimportant differences in its structure as well as in size. 

 Unfortunately the ' Challenger ' description of it is much too 

 meagre to allow of a satisfactory comparison ; but if the 

 details of the figure may be trusted, the avicularia represent 

 two different types. The question can only be settled by an 

 examination of the ' Challenger ' specimens, which I have 

 not had the opportunity of making in time for this paper. 



Ibid. (p. 16 Sep.). 



Mernbranipora villosa, sp. u. 

 Syn. ? Flustra Isahelleana, d'Orbigny, Voyage &c. pi. viii. 

 D'Orbigny, in his ' Voyage dans I'Amerique mdridionale,' 

 has described a species under the name of Flustra Isahelleana, 

 which presents some rather striking points of resemblance to 



* ' History of Brit. Mar. Polyzoa,' p. 307, pi. xxxiii. fig. 6. 



