128 DEVONIAN FAUNA. 
4. RHYNCHONELLA TRILOBA, Sowerby, sp. 
1840. Arrypa TRILOBA, Sowerby. Geol. Trans., ser. 2, vol. v, pt. 3, pl. lvi, fig. 14. 
1854. TEREBRATULA FoRNICATA, Schnur. Paleontographica, vol. iii, p. 177, pl. 
xxiil, figs. 1 a—e. 
1865. RyncHoneLia TRILOBA, Davidson. Brit. Foss. Brach., vol. iii, pt. 6, p. 64, 
pl. xii, figs. 1—7. 
1882. — — — Ibid., vol. v, pt. 1, p. 47, pl. ii, fig. 21. 
1885. _ — Maurer. Abhandl. Grossh. Hessisch. Geol. Landes., 
vol. i, pt. 2, p. 210, pl. ix, figs. 39—40 a. 
Localities. —From Lummaton there are twenty-five specimens in my Collection, 
three in the Woodwardian, and two (?) in the Torquay Museum. From Wolborough 
there are seven fine specimens in Mr. Vicary’s Collection, four in the Museum of 
Practical Geology, and one in the British Museum. 
Remarks.—My specimens show various degrees of development, some ap- 
proaching the flat variety figured by Davidson in his Supplement. Besides the 
above I have found some very small flat specimens at Lummaton which probably 
are the young form. 
Maurer identifies Rh. fornicata, Schnur, sp., with this species. 
5. RHYNCHONELLA TRILOBOIDES, n. sp. Pl. XV, fig. 3. 
Description.—Shell sub-oval, very transverse, with rounded angles. Beak 
small, recurved, narrow, and rather elevated, with arching sides. Ventral valve 
rather convex, with a broad central sinus, which is well marked in front. Dorsal 
valve equally convex both vertically and horizontally, bearing a broad, low but 
very distinct, rounded fold. Lateral margins deeply convex. Front margin 
gently convex. Surface ornamented with rather numerous elevated, rounded 
ribs, which are very irregular and unequal in size and direction, and do not seem 
to reach quite to the apex. 
Size.—Length, 18 mm.; width, 23 mm.; depth, 13 mm. 
Locality.—I have ten specimens from Lummaton, most of which, however, are 
very imperfect. 
Remarks.—This shell approaches Rh. triloba on the side of Sowerby’s Atrypa 
latissima. Mons. Ghlert, however, intimates to me that it cannot be classed with 
that species, and my specimens are clearly distinguishable in several particulars, 
e.g. the much sharper and more elegant beak, the more irregular, larger, and fewer 
ribs, the lower and more defined fold, the more convex vertical dorsal contour, 
and the less produced front margin. 
