Thomas Davidson — Spiral-Bearing Brachiopoda. 7 



abruptly by a broad curve so as to form the first coil of the spiral, 

 the giving forth at about half their length of an inwardly con- 

 verging lamella d, h, by vi^hich both spirals are connected, the 

 extension upwards of a narrow lamella h, f, g, and its bifurcation at 

 g, remind us of Athyris, although differing in minor details, but at 

 the point g the bifurcating process is short and small and does not, 

 as in Athyris, give rise to a curved supplementary lamella. Now, as 

 Mr. Glass has worked out a large number of Athyris planosulcata 

 and of Meristella tumida, and as they have one and all constantly 

 shown the same characters, we are justified in supposing they are 

 persistent in each species of the same genus. 



Prior, however, to Mr. Glass's researches, in vol. iv. of the 

 Palaeontology of New York, p. 298, Prof. J. Hall described and 

 illustrated the spiral appendages, their attachment to the hinge-plate, 

 and their connecting system of lamellae, in Meristella arciiata (Hall) 

 — a species so near in shape to our English Meristella tumida as to 

 make one question whether it is not specifically the same. In Prof, 

 Hall's figures the short forked process (g' in our figures of M. tumida) 

 extends and forms a complete circle, the branches uniting again 

 at the point where they originated. Feeling some misgivings 

 as to the correctness of Prof. Hall's illustration, in this particular, I 

 wrote to Mr. Whitefield, who drew the figures, for some further ex- 

 planations, and in his answer, dated the 6th of October, 1878, he 

 says, " With regard to Meristella I can assure you there is no error 

 in the figures published. Yesterday I took several of the specimens 

 of Meristella nasiita, M.lcems and M. arcuata, and examined them; 

 they all show the same features as given in the diagram in the text 

 of vol. iv. Palaeontology of New York. . . . They are not sections, 

 but silicified specimens treated with acid, and the spire and loops are 

 entirely revealed to the light. All the specimens described by Prof. 

 Hall are now in the American Museum of Natural History." I 

 have never seen the American specimens of Meristella, but I can 

 assert that those worked out by Mr. Glass leave no room for mis- 

 conception, and as they have all been most liberally presented to me 

 by him, as well as all the other worked specimens of other species, 

 they can be inspected by any one taking an interest in the subject. 

 By comparing the diagrams given of Meristella and Athyris, the 

 differences they present can be recognized better than they can be 

 described by words. 



NUCLEOSPIKID^. 



In this group would be included Nudeospira, Hall, Betzin, King, 

 and Bhynchospira, Hall. In the twelfth annual report of the 

 Kegents of the University of the State of New York, p. 24, 1859, 

 Prof. James Hall gives a complete and illustrated description of his 

 genus Nudeospira, exemplified by Nudeospira ventricosa, Hall. 



At my request the Eev. Norman Glass has worked out in the 

 fullest manner the characters of the spirals in Nudeospira pisiim, 

 their attachment to the hinge-plate, and the process connecting the 

 spiral coils. His researches and prepared specimens agree in all 



