PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 585 
anterior half costate ; fold generally with 3 costae, sulcus with 2, and flanks with 
I or 2 depending on age. 
Pedicle valve slightly less deep than the brachial one, moderately convex in 
lateral profile and with the maximum convexity slightly posterior to the middle; 
anterior profile broadly and gently convex; umbonal and median regions swol- 
len, the maximum swelling just posterior to the sulcus; sulcus originating at the 
middle, wide and shallow; tongue long, its angle of geniculation not quite reach- 
ing a right angle; flanks narrowly rounded; beak fairly long and strongly 
incurved. 
Brachial valve fairly strongly convex in lateral profile ; anterior profile strongly 
domed and with precipitous sides. Umbo and median areas strongly swollen; 
fold originating at the middle, partaking of the general profile and only moder- 
ately elevated at the front. Flanks narrow and swollen. 
Measurements in mm.— 
Brachial Hinge 
Length length Width width Thickness 
BU UGE IE Me ox jaja aiecs wo, 56.6 g's s 3) 0'hys 9.8 8.7 10.1 3.1 8.0 
Paratyoe. (PELTFZOD) oc cc sos aes es 8.2 7.4 9.0 > 6.0 
ot ar Ly, Mn alan a 9.5 8.7 8.7 ? 6.7 
i (zaer70d) PI. 8.8 78 G 2.8 6.9 
Types.—Holotype: 111170a; figured paratype: 111170d ; unfigured paratypes: 
I11170b,c. 
Horizon and locality—Crown Point formation (loose but from Brainerd and 
Seely’s section 2, zone 3 of Division B) on Plattsburg (15’) Quadrangle, New 
York: At Chazy; at the normal school 4 mile north of Plattsburg; Valcour 
Island. 
Discussion.—This species is characterized by its compact form, the strongly 
geniculated pedicle tongue, the anteriorly costate and posteriorly nude exterior, 
and strong convexity. The species suggests C. obesa from the Trenton (Rock- 
land) limestone, but the tongue is less geniculated and the costae extend farther 
posteriorly on the valves. It is also similar to C. oklahomensis, but it is larger 
and more convex although less strongly costate. Camerella ventricosa is a larger 
and more strongly costate species than C. tumida from Newfoundland. 
CAMERELLA VOLBORTHI Billings 
Plate 110, C, figures 8-11; plate 116, A, figures 1-5 
Camarella volborthi Brrtines, Canadian Nat. Geol., vol. 4, p. 301, 1859; Geol. Canada, p. 143, 
fig. 77, 1863 Hai and Crarke, Pal. New York, vol. 8, pt. 2, p. 220, pl. 62, figs. 13-18 
(not 11 and 12), pl. 84, fig. 42, 1894.—Mutter, North Amer. Geol. Paleont., p. 338, 
fig. 546, 1889—ScHucHERT and Cooper, Mem. Peabody Mus. Nat. Hist., vol. 4, pt. 1, 
pl. 25, figs. 5, 20-22, 28-30, 1932. 
This is one of the largest species of the genus now known. It may be recog- 
nized by this fact and by its almost completely smooth exterior. Costae are con- 
fined to the margins of the valves and are generally not strongly developed. 
Types——Lectotype: G.S.C. 1148a; paratype: G.S.C. 1148b; figured hypo- 
type: 117148a; hypotype: G.S.C. not numbered. 
