118 DEVONIAN FAUNA. 
3. ATRYPA TRIGONELLA, Davidson. Pl. XIII, figs. 11, 12. 
1882. ArTRYPA ? TRIGONELLA, Davidson. Brit. Foss. Brach., vol. v, pt. 1, p. 40, 
pl. i, figs. 19, 19a, 6. 
? 1886. — RETICULARIS, var. ASPERA, @hlert. Ann. Sci. Géol., vol. xix, 
p- 30, pl. ii, fig. 23. 
? 1889. — ASPERA, Toll. Mém. Acad. Sci. St. Pétersbourg, ser. 3, vol. xxxvii, 
No. 3, p. 25, pl. u1, fig. 15. 
Remarks.—About fifteen specimens in my Collection and one in the Wood- 
wardian Museum can be referred with more or less certainty to this species, and 
they go to prove its close proximity to A. reticularis. A careful comparison of 
these with Davidson’s type shows its trigonal shape, median depression, and 
truncated beak to be accidental. Its ribs are very similar in character to those 
of A. aspera, but more numerous, much steeper, and constantly divaricating. 
The transverse ornament is much the same but not so pronounced. ‘The beak is 
high, and the area and the foramen large. The shell-structure is very thick, 
loose, and perishable. 
Nine other small and doubtful specimens have closer ribs and a smaller umbo, 
and thus come halfway between it and the more typical shapes of A. reticularis. 
Upon the whole it can only be regarded as a rather doubtful species, and is 
perhaps an argument in favour of uniting the whole group into a single species. 
It has the beak of A. desquamata, the transverse ornament of A. aspera, and to an 
exaggerated degree the divaricating ribs of A. reticulata. The specimens are all 
small and flat. 
The ornamentation of Atrypa insolita, Barrande,' is almost exactly similar. 
4, ATRYPA ASPERA, Schlotheim, sp. 
1813. TEREBRATULITES asPER, Schlotheim. Leonhard’s Taschenbuch, vol. vii, pt. i, 
pe 4 pl. a, fies. 
1854. ATRYPA SQUAMIFERA, var. ASPERA, Schnur. Paleontographica, vol. iii, p. 
181, pl. xxiv, figs. 4 f—~. 
1865. —  RETICULARIS, var. ASPERA, Davidson. Brit. Foss. Brach., vol. iii, 
p- 57, pl. x, figs. 5—8. 
1882. — aspeERA, Davidson. Brit. Foss. Brach., vol.v, pt.1, p. 40, pl. x, fig. 5. 
1882. — —  Barrois. Mém. Soc. Géol. Nord, vol. 1, p. 265. 
1885. —  RETICULARIS, var. ASPERA, Maurer. Abhandl. Grossh. Hessisch. 
Geol. Landes., vol. i, pt. 2, 
p- 183, pl. vii, figs. 35, 36. 
11879, ‘Syst. Sil. Bohéme,’ vol. v, pl. xxviii, figs. 4, 110, Et. E. 
