1014 THE PALEONTOLOGY OF MINNESOTA. 
[Hormotoma gracilis. 
they have or have not been derived from elongated species of Lophospira like 7 
bowdeni Safford. 
Besides the five Trenton and Cincinnati species about to be described, we refer 
here Murchisonia anna, M. simulatrix and M. vesta, three species described by Billings 
as occurring in the Calciferous in Canada; M. gracilens Whitfield from the same 
horizon in Vermont; M. procris Billings, from the Black River group of Canada; 
M. moniliformis, M. obtusangula and M. subplicata, Gothland species described by 
Lindstrom; and M. hebe Billings, Gaspé of Canada. WM. cingulata Hisinger (as figured 
by Lindstrém) and MV. egregia Billings, have the band too low to be counted as typical 
members of the genus, yet, itis probably best to place them here. We have already 
mentioned M. attenuata Hisinger, and M. artemesia Billings. M. agilis Billings, 
Quebec group, Canada, as is the case with other species described as Murchisonia, 
may belong here but is not sufficiently known to permit us to say that it does. M. 
teretiformis, of the same author, provided the Manitoba specimens identified by 
Whiteaves with this species are really the same as Billings’ original types, has all 
the characters of Hormotoma, despite the great size which this shell attains.* 
(Ehlert describes two species from the Devonian of France as M. (Hormotoma) 
lebescontei and M. (H.) clavicula. The same author proposes Groniostropha as a section 
of Murchisonia and includes in it several of the species that we refer to Hormotoma. 
If Goniostropha is to be recognized it must be for the reason given on page 1012. If 
these are not sufficient then the American species M. desiderata, M. maia and M. leda 
of Hall, together with some of the European shells which (hlert places in his 
proposed section, must be regarded as congeneric with the Silurian species of 
Hormotoma. As defined by (Ehlert, Goniostropha is clearly an incongruous 
assemblage. 
Hormotoma GrRaciLis Hall, and varieties. 
PLATE LXX, FIGS. 18—36 and ?42—43, 
Murchisonia gracilis HALL, 1847, Pal. New York, vol.i, p. 181 (not SALTER, 1859, Can. Org. Rem., Dec 
1, p. 22.) 
Murchisonia angustata HALL, 1847, Pal. New York, vol. i, p. 41.* 
Comp. Murchisonia gracilens WHITFIELD, 1889, Bull. Amer. Mus. Nat. Hist., vol. ii, p. 53, pl. vm, 
fig. 14. 
* We are strongly inclined to doubt that the Manitoba specimens, which are from the Trenton limestone (Fusispira or 
Maclurea bed), are specifically the same as the Hudson River group, Anticosti, originals of M. teretiformis. The apical 
angle in the former is 35° or more, while Billings gives the angle for the Anticosti types at 27°. Since the foregoing was 
placed in the printer’s hands, Mr. J. F. Whiteaves has kindly sent us the two best specimens of these Manitoba and Anticosti 
forms in the museum of the Canadian survey. Asaresult of our comparison, we are now firmly convinced that the two 
forms are specifically distinct, differing from each other in the same manner as H. bellicincta and H. trentonensis, The 
Manitoba species resembles the former, having more whorls, especially in the upper half of the spire, than the true A. 
teretiformis. 
+ As will be noticed, the description of M. angustata occurs on an earlier page in the work cited than that of M. gracilis, 
and if we followed the usual custom in such cases the first name would have been adopted for the species instead of the 
Second. But asthe date and authority for the two names is the same, and as the name angustata has been scarcely recog. 
nized while M. gracilis has been described and quoted perhaps hundreds of times since 1847, it is evident that the latter has 
the better right to be 1etained for the species. 
