GASTROPODA. 963 
Lophospira.] 
ensis Safford sp., L. perlamellosa Ulr., L. perforata U. and §., L. spironema U, and 8. 
L. tennistriata Ulr., L. conradana U. and §., L. gothlandica Uly.* 
2. Bowdeni subsection:—High shells, eight to twelve whorls, less angular than 
in preceding subsection. Species: L. bowdeni Safford sp., L. producta Ulv., L. augus- 
tina Billings sp., 2. major Hall sp., L. macrospira Hall sp. 
3. Cicelia subsection:—Differs from 1 in having a much higher spire, and from 
2 in having more numerous and more sharply angular volutions. Species: L. cicelia 
Billings sp., L. estella Billings sp., L. extenuata Hall sp. 
4. Serrulata subsection:—Distinguished from 1 by the plate-like extension and 
wavy character of the central part of the peripheral carina. Only known species: 
L. serrulata Salter sp. 
B. Bicincta section:—Lines of growth curving very slightly, or not at all, back- 
ward to the peripheral keel, the apertural notch being very shallow. 
: 1. Bicincta subsection:—Surface markings fine, generally quite regular, sharply 
elevated and closely arranged. Species: L. bicincta Hall sp., L. quadrisulcata U. and 
S., L. obliqua U. and 8., L. humilis Ulr., L. concinnula U. and 8., L. fillmorensis U, 
and 8., L. aspera Billings sp. 
2. Tubulosa subsection:—Similar to preceding, but surface markings much 
stronger, lamellose and imbricating, particularly on the band. Species: L. tubulosa 
Lindstrom sp., L. Jaqueata Lindstrom sp., both from the Upper Silurian of Gothland. 
3. Imbricata subsection:—Relatively high small shells, with coarsely lamellar 
imbricating lines of growth; the latter turn backward on the basal portion of the 
whorl very soon after leaving the peripheral band, the aperture being unusually 
oblique. Species: Murchisonia imbricata, munda, tortuosa, cochleata and perhaps 
cancellata, all Upper Silurian of Gothland and described by Lindstrém. Unknown 
in America except by an undescribed species in the Clinton iron ore of New York. 
4, Holmi subsection :-—Lines of growth fine and equal as in the Bicincta sub- 
section but with a direction as in the preceding. Only known species: Plewrotomaria 
holmi Lindstrém (Gothland.) 
5. Helicteres subsection:—Agrees in all respects with the Bicincta subsection 
excepting that the last whorl or two is free. Only known species: L. helicteres 
Salter sp.t 
C. Robusta section:—Shells rather short, whorls comparatively rounded, ventri- 
cose, scarcely angular even at the peripheral band, which is distinctly trilineate. 
*The name Lophospira gothlandica is proposed for the shell which Lindstrém describes from the Upper Silurian strata of 
the island of Gothland as a species of Plewrotomaria under Hall’s specific name bicincta, It is beautifully illustrated on 
Se 8 oe Oe er 
+Murchisonia soluta and M. tropidophora of Whiteaves. from the Guelph of Canada, for which the subgenus Loxoplocus is 
proposed by Fischer (Manual Conch,, p, 847; 1885,) may belong to this subsection, but in the absence of reliable information 
respecting the characters of the peripheral band and apertural sinus, we prefer to leave them unclassified. 
