ATRYPA. 119 
1885. ArTRypa aspeRA, Wenjukof. Faun. Dev. Syst. N.W. und Cent. Russl., p. 
519, pl. vi, figs. 2a, b. 
1887. —  BIFIDHFORMIS, Tschernyschew. Mém. Com. Géol., vol. iii, pt. 3, 
p. 83, pl. iv, fig. 20, and pl. x, 
figs. 14 a—e. 
1891. —  RETICULARIS, Whiteaves. Contrib. Canad. Palxont., vol. i, pt. 3, 
p. 229, 
? 1891. — — var. ASPERA. Ibid., p. 229. 
Remarks.—This species seems comparatively rare. I have fourteen specimens 
from Lummaton; eleven more are in the Woodwardian Museum, and two in the 
Bristol Museum. There are twelve in the Torquay Museum from that place, and 
two from Wolborough. Mr. Vicary has twenty specimens, and the Museum of 
Practical Geology eight, from Wolborough. 
These specimens are of comparatively small size. The ribs are very low, 
coarse, rounded, and simple instead of divaricating. The regular and distant 
crossing ridges give the surface a nodulous appearance. The beak seems small, 
low, and incurved. My strong impression is that we have in this form a distinct 
species. It is certainly separated from A. reticularis proper by the group of 
A. trigonella ; and, even if that form should be regarded as a variety of the 
former shell or of A. desquamata (= A. compressa), the shape and simplicity of 
the ribs in the present species may prove a distinctive feature. Passage-forms do 
not appear to exist. 
Atrypa spinosa, Hall,’ A. hystrix, Hall,’ and A. aspera, v. occidentalis, Hall,’ do 
not seem to me identical with this species, but closely allied. 
5. Arrypa? Leet, Davidson, sp. 
1882. RuyncHonetta Leet, Davidson. Brit. Foss. Brach., vol. v, pt. 1, p. 47, 
pl. ui, figs. 15, 15 a. 
Remarks.—Davidson has considerably restored the figure of the specimen 
which he makes the type of this species. I have no additional evidence to bring 
forward, as I have not found any further example. I hardly like, in view of his 
identification, to suggest the possibility of its being an abnormal form of 
A. reticularis, but I must confess great doubts as to whether the marginal 
obliteration of the ribs is not really due to the peeling away of the exterior layer 
of the shell, which is certainly much confused with the matrix. The careful 
examination of a large number of specimens of Devonian Atrypx since I sent my 
1 1867, Hall, ‘Pal. N. Y.,’ vol. iv, pt. 1, p. 322, pl. litia, figs. 1—14, 18, 24, 25. 
2 Ibid., p. 326, pl. liti a, figs. 15—17. 
8 Tbid., p. 322, pl. liiia, figs. 19—21. 
