450 Transactions. 



Art. XL. — Terminology for Beak atid Foramina] Development in 



Brachiopoda. 



By S. S. BucKMAN, F.G.S. 



Communicated by Dr. J. Allan Thomson. 



[Publication authorized by the Publication Committee under Regulation 5, (a). (2) ; issued 



separately, 26th Avr)ust.~\ 



The previous communication made by me on this subject, entitled " Termin- 

 ology for Foraminal Development in Terebratuloids (Brachiopoda)," which 

 appeared in the Transactions of the New Zealand Institute, vol. 48, 1916, 

 pp. 130-32, seems to have provided terms which are found to be useful and 

 convenient. It has also received commendatory notice in Revue critique de 

 Paleozoologie, 1918, pp. 37-39, though the writer of the review has fallen 

 into an error which may be misleading. For these reasons I am tempted 

 to pursue the subject somewhat further. 



The error committed by the writer in question is this : He says (p. 38), 

 " M. Buckmau a indique graphiquement la position du foramen circulaire 

 par rapport a la ligne de separation des valves." This is a complete 

 misunderstanding of the little diagram in my paper. The position of 

 the foramen is not indicated with regard to " the line of separation of the 

 valves," but in regard to the line of the beak-ridges {la ligne des carenes 

 laterales du crocket) — quite a different matter. The line of the beak-ridges 

 is the convenient and necessary datum-line for the jiurpose, and it is this 

 line which is represented by the horizontal lines in my diagram. This line 

 of the beak-ridges separates a more or less defined area, the pseudo-area 

 or cardinal area of the ventral valve. 



There is another little matter for notice in this quotation. The circular 

 foramen is not a necessity in regard to these terms. That the foramen was 

 indicated by a circle was only a matter for convenience in printing. The 

 position of the foramen is one observation ; the shape of the foramen is 

 another — quite distinct ; and the condition of the foramen is a third. 

 These must be kept separate, for all sorts of combinations are possible. 



The shape and some of the developmental phases of the foramen come 

 under the terms " trigonal," '' subtrigonal," " elliptical," '' circular," and 

 so forth — see my memoir, "The Brachiopoda of the Namyau Beds," 

 Palaeontologia Indica, n.s., vol. 3, part 2, 1917 (1918) ; but other 

 terms, like " obtrigonal,"* " oblong," '' trapezoid," &c., will be required. 

 The condition of the foramen I have described by such terms as " telate, ' 

 " marginate," " auriculatc," " attrite," '^ labiate/' '■ renovate." Some of 

 these conditions are found only with the hypothyrid position, others belong 

 to the mesothyrid in the main or to the epithyrid. Particulars are given 

 in the work above quoted under the headings of " Ehynchonellidae " and 

 " Terebratulidae," but I am unable to cite the page-numbers, as the only 

 copy which has yet reached me is at the binder's. 



Returning now to the position of the foramen, it may be desirable to 

 have terms by which to indicate its position in regard to the line of the 



* With apex pointing anteriorly. 



