BRITISH SILURIAN BRACHIOPODA. 109 



made a perforation in the American type just at the place where the bifurcated end of the 

 loop should occur. 



Meristay Meristella, and WhitfiekUa are evidently closely related. If the forked part 

 of the loop in W. tumida were prolonged in the shape of a ring it would be a Meristella, 

 but since it is never so in Wh. tumida, it is even better distinguished than Meristella is 

 from Merista. I have therefore proposed for the A. tumida of Dalman and similarly- 

 constructed species a new genus or sub-genus, Whitfieldia, after Mr. R. P. Whitfield, of 

 the American Museum of Natural History, New York, who during many years assisted 

 Professor Hall by developing in an admirable manner the interiors of the spiral-bearing 

 genera of several Brachiopoda described by him in his magnificent work on the 

 ' Palaeontology of New York,' and by drawing for that work many of the beautiful plates. 



Professor James Hall has worked very earnestly for many years on the Brachiopoda, 

 and has been able, not only to contribute largely to our knowledge with respect to the 

 species that occur in the Palaeozoic rocks of the United States, but also to establish many 

 new genera from a careful study of their internal characters, a work that will ever give 

 him great credit. Much more, however, still remains to be discovered, and I trust 

 that both he and other palaeontologists will continue the work so successfully carried on 

 and for so long a period. I wish also on this occasion to acknowledge the highly valued 

 help I have at all times received from Professor Hall. 



Family — Atrypid/E, Ball, 1877. 



Genus — Atrypa, Dalman, 1828 = ^/jfnym^^a, d'Orb., 1847. 



10. Atrypa reticularis, Linne, sp. Dav., Sil. Mon., p. 129, PI. XIV, figs. 1, 2; and 



Sil. Sup., PI. VI, figs. 14, 15, and PI. VII, 

 figs. 1— G. 



Atrypa reticularis, Bav, Geol. Mag., New Series, vol. viii, January and April, 



1881. 



The external characters of this well-known species have been described at p. 130 of 

 my 'Silurian Monograph ;' but in June, 1867, when I published my description, speci- 

 mens showing the whole internal characters were not in my possession. In the explana- 

 tion of PI. XIV, in a footnote, I, however, referred to Mr. R. P. Whitfield's ' Observations 

 on the Internal Appendages of the Genus Atrypa,' published in 1806.^ The position 



^ Printed in advance for the ' Nineteenth Report on the New York State Cabinet,' December, 1806. 



