American JPaUeozoic Bryozoa. 



133 



nearly both with the figures and description of M. mammulata, given 

 by Milne-Edwards and Haime, is the type c, which Nicholson has 

 named M. molesta. The figure given by the same authors of M. 



frondosa (pi. xix., fig. 5), represents such a characteristic specimen of 

 a common variety of .Nicholson's M. mammulata, that I am rather 

 surprised to find that he does not recognize it, but considers that his 

 specimens of a species described by Rominger, 'under the name of 

 Chaitetes decipiens, " present such a close resemblance to the figure of 

 M. frondosa, D'Orb., given by Edwards and Haime, that he (I) can 

 hardly believe that they are not in reality identical." In opposition to 

 this belief, which I must regard as a sincere one, I can only urge that 

 I did not allow myself to become fully convinced of the validity of the 

 ground I have taken, without corroborative evidence. This I obtained 

 b} T showing Edwards and Haime's figure of M. frondosa, to a number 

 of Cincinnati collectors and students in this branch of palaeontology. 

 Without a single exception all, almost immediately, recognized that 

 the figure represented an example of an abundant variety of Nicholson's 

 31. mammulata. There i« one feature represented by the figure in 



•question, that I will venture to say, Dr. Nicholson has never seen on 

 any specimen of the form he has identified with M. frondosa, D'Orb. 

 (Ghcetetes decipiens, Rom.), and that is the subcylindrical character 

 of the lower right hand portion of the frond represented by their fig. 5, 

 pi. xix. In his remarks upon M. frondosa and decipiens, Nicholson, on 

 page 223 of his "Palaeozoic Corals," makes the following remark, and 

 misquotation: " The only point worthy of notice in this connection is 

 that Rominger himself recognizes (Pro. Acad. Nat. Sci., Phil., 1866, 

 p. 116), the similarity of his M. decipiens to M. frondosa, D'Oib., and 

 merely says that it is ' more delicate in all respects,' and that its inter- 

 tubular tissue is less developed.' 5 To distinguish his Chaitetes 

 decipiens (M. decipiens) from 31. frondosa, Rominger says: "This 

 species has likewise much similarity with Ch. frondosus, but it is 

 more delicate in all respects, and in Ch. frondosus the intertubular 

 tissue is considerably less developed, its tubules being usually in im- 

 mediate contiguity." However vague the above differentiation may 

 be considered, it is nevertheless certain that by Ch. frondosus, 

 Rominger, meant the 31. mammulata of Nicholson (not D'Orbigny). 

 Furthermore, we find that Milne-Edwards and Haime's description of 

 Ch. frondosus, D'Orb., applies in all respects to Nicholson's M. mammu- 

 lata, and not to 31. decipiens, Rominger (M. frondosa, Nich.); and 

 although Nicholson states that he is not acquainted with any 



