8 Prof. W. King on Spirifer cuspidatus. 



men, though they are arranged somewhat more regularly. 

 Fibres well displayed. 



No. 5. — Six sections : none showing decidedly any perfora- 

 tions ; a few faint markings, almost as translucent as the fibres, 

 may, I suspect, represent them. The fibres, straight and 

 twisting, are very well displayed. 



No. 6. — Specimen presented by Professor Harkness. I have 

 prepared twenty sections (some very thin) taken from all parts 

 — sides, median fold, and area. They were not so easily rubbed 

 down as those from Messrs. Birmingham and Morton's speci- 

 mens. Most of the sections exhibit the fibres, beautifully trans- 

 lucent, running straight out or winding about, and strikingly 

 resembling those of the recent Rhynchonella psittacea. Not 

 one shows anything that could be pronounced to be a perfora- 

 tion ; but, as usual, obscure markings are present. The sub- 

 shell-layers display, in places, slightly raised oval impressions, 

 the same as those seen in Mr. Birmingham's specimen. 



It is important to observe that every one of the previous 

 specimens is undoubtedly furnishedj as will be seen hereafter, 

 with the canaliferous septum. 



No. 7. — This specimen is small, and appears to be a dwarfed 

 individual, judging from the unusual thickness of its valves. 

 It is from Millicent, and is the original of fig. 19, pi. 8, of 

 Mr. Davidson's ^ Carboniferous Brachiopoda.' Dr. Carpenter, 

 who has cut the specimen through its umbonal portion, ^' feels" 

 himself '^justified in confidently asserting that it is essen- 

 tially imperforate." He has given a representation of a 

 ^^ transverse section " of its umbone to show that the ^' dental 

 laminae are unconnected by any transverse septum, and that 

 there is no vestige whatever of the canal"*. On the latter 

 point some considerations favouring a different view will here- 

 after be produced. Mr. Davidson has, in the most liberal 

 manner, presented me with the two halves, left after Dr. Car- 

 penter had cut the specimen, to operate upon, as I thought fit, 

 for the benefit of science. 



Twelve sections were obtained, all hard and imperforate, like 

 those of the last specimen. Indeed the sections from both are 

 perfectly identical, not only in the absence of perforations, but 

 in the distinctness, disposition, and translucency of the fibres. 



That this specimen "exhibited not the smallest trace of 

 perforations" to Di\ Carpenter is quite admissible. It is ne- 

 cessary, however, to state that one of my sections shows a few 

 scattered spots, which approach to some of the obscure mark- 

 ings noted as occurring m the precited sections of perforated 



* Ann. & Mag. Nat. Hist. July 1867, p. 72, fig. 4. 



