FLORIDAN BRYOZOA. 31 



In the neighbourhood of the P. violacea, also, is to be placed the true Porina 

 lichenoides *), that once I saw in the Paris-museum, in the Jardin des Plantes, although 

 it was in an all too bad condition for making out, with certainty, its specifical distinc- 

 tion, in relation to its nearest allies. Yet, its most important character seeins to be 

 the more lateral position of the avicularium. 



In comparing the structure of the preceding Porince with the Anarthropora mon- 

 odon, besides the more cylindrical raising of the aperture, quoted as the distinctive 

 character of the genus Anarthropora, one will find the chief difference to be the re- 

 lation between the median pore and avicularium. For, in the Anarthropora monodon, 

 the avicularium, in its development, covers that pore. The distal avicularium, devel- 

 oped in that species, evidently corresponds to the similarly placed organ in the Eschari- 

 pora stellata. Thus, the Anarthroporidan structure very naturally is connected with the 

 other Eschariporidan types, and, indeed, it is a matter of opinion, how long we ought 

 to go, in our generical dismembering of a natural family. Formerly, as the family 

 then was known, I thought it very natural to distinguish the tubular raising of the zooecial 

 aperture as the character of a separate genus to be placed at the side of the articulated 

 Onchopora, for, by them, to remember, in this family, of the common tendency of develop- 

 ment of the escharines towards the celleporine construction. But the name of Anarthro- 

 pora, as I expressively remarked, was created only for replacing that of Quadricellaria, 

 constituted by Särs, but, before him, used by D'Orbigny for the name of another bryozoan 

 genus. Now Mr. Norman 2 ) has made another use of Anarthropora ; and, as I hope soon 

 to receive that "entire rearrangement of the Membraniporidaä" 3 ), which he has promised 

 shortly to carry out, it will be the most prudent in the mean time to follow his 

 opinion. 



Anarthropora minuscula 4 ) (Pl. VI, fig. 141). 



In the arctic sea at first I distinguished this form as an unarmed variety of 

 Anarthropora, monodon. From that form, however, it differed, as I then remarked, by its 

 smaller size, its constantly lower degree of calcification and its more uniformly cylindrical 

 secondary raising of the aperture. All these differences very plausibly seemed to be 

 deduced from a supposed lower degree of development; and, for the sake of the inter- 

 mediate forms, I could not give any other constant characteristic than the presence 

 or absence of the avicularium. Now, this characteristic, also, löses its value, because 

 on Myriozoum, from a depth of 42 fathoms, W. off Tortugas, Pourtales has taken 

 one little colony of Anarthropora minuscula provided with avicularium of the typical form 

 and position. Yet, the specimen is all too little for deciding, if, in its further devel- 

 opment, it should have assumed the typical appearance of the true Anarthropora mon- 

 odon. The whole colony, just in the beginning of its growth, contains only five zooecia. 



1 ) Eschara lichenoides, Lam, Anim. s. Vert., vol. II, ed. 1, p. 176; ed. 2, p. 268. 



2 ) Brit. Assoc., 1868, Rep., p. 309. 



3 ) To that family, Anarthropora, after Norman, should be referred. 



*) Krit. Fört., Öfvers. Vet. Akad. Pörh., 1867, Bih, pp. 7 et 65, tab. XXIV, figg. 20— 22. 

 Lepralia tubulosa (?) Norm., Brit. Assoc. 1868, Rep., p. 308. 



