80 Rev. N. Glass—The Spirals of the Brachiopoda. 
and the bifurcation. In Meristella, Hall (Whitfield, 1860), each side of 
the bifurcation at the end of the simple loop curves round upon itself 
so as to form a ring. This loop, which thus contains two rings, 
occurs also in Merista. In Athyris, M‘Coy (Davidson, 1858), there is 
a roof-like expansion at the end of the simple loop, from the top of 
which two accessory lamellz curve upwards and backwards to the 
inside of the primary lamelle, and are continued downwards to the ~ 
centre of the spirals on the dorsal side. In Kayseria, Dav. (Glass, 
1882), at the end of the simple loop there is a single rounded process, 
and at the end of this process the loop bifurcates in an upward direc- 
tion, as in Athyris. The accessory lamella, however, do not terminate 
as in Athyris, but are continued between the main coils to the end 
of the spirals. 
Thus there are fourteen forms of loop known, most of which have 
been recently discovered. 
Dr. Waagen describes the interior of the genus Eumetria. He 
says, ‘The primary lamellz are very strange in their development. 
They show broad wing-like expansions at their origin, which are 
sometimes very strongly developed.” This “ very strange” develop- 
ment had been previously worked out by me, and figured by 
Davidson in 1881 as existing in Athyris plano-sulcata,! in which the 
primary lamelle near their origin increase in width—the increased 
width extending downwards nearly to the centre of the spirals on 
the dorsal side. Dr. Waagen gives a description of the loop of 
Eumetria, and it seems to be similar to the simple loop of the 
Nucleospiride, with the exception that the loop commences nearer 
to the origin of the primary lamella, and has a downward direction 
between the spirals. Supposing this to be correct, the loop of 
Eumetria forms an addition to the number of loops previously 
worked out. 
Davidson gives two figures of the loop of Uncites? in his 
Devonian Supplement, 1882. From these figures the loop would 
seem to be simple and transverse as in Spiriferina, with the excep- 
tion that there is a thickening at the centre of the loop, which on 
the upper side amounts to a short spinous projection. ‘The attach- 
ments to the hinge-plate are straight, as in the Spiriferide. 
With the exception of the spirals in Thecospira, and the loops in 
Spiriferina, Humetria, and Uncites, all the particulars given above 
have been carefully verified by my own preparations. 
P.S.—I have made no reference in the above article to the eminent 
Paleontologists by whom the respective genera were determined 
and described. The discoveries of Mr. Whitfield were described 
by Prof. Hall, of Albany, U.S. My own were described by Dr. 
Davidson, whose recognition of any assistance I may have rendered 
him in his great work was always most generously made. (As see 
Grot. Mae. 1881, loc. cit.) 
1 See Groz. Mae. 1881, Dec. II. Vol. VIII. p. 5, Figs. 2 and 3. 
2 See Grou. Mac. 1881, Dec. II. Vol. VIII. p. 153, Figs. 20 and 21. 
