396 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 42. 



STREPTOTROCHUS SULCATUS, new species. 

 Plate 50, fig. 9. 



The type of this form is shghtly crushed, but shows about the same 

 size, angle, and number of whorls as in Streptotrochus ione. The first 

 whorl visible (which is probably the second whorl) is simply convex, 

 the third, fourth, fifth, and sixth whorls are each marked by distinct 

 revolving groove or sulcus on the right side of the carina; and the 

 carina on the outer, left side is strong but rather broad. The fine 

 concentric fines are distinct, but the longer irregular concentric fold- 

 ings seen in other specimens are wanting. 



Locality. — Same as Streptotroclius ione. 



Holotype.—Csit. No. 58445, U.S.N.M. 



REMARKS ON THE SPECIES OF STREPTOTROCHUS. 



In the above descriptions I have given the distinguishing characters 

 of four specimens selected from a number exposed to view on a single 

 slab of shale about 6 by 3 inches in dimensions. The locafity from 

 which the slab came is probably the same from which Shaler obtained 

 the specimens called by him ^' Murchisonia desiderata?" ^ 



The' specimens are not MurcTiisonia, and none of the specimens 

 from the locafity, or from anywhere on Moose Island, have the long 

 slender spire of Hall's species mentioned by Shaler. The four figures 

 given on plate 50 exhibit the general characters which are alike to such 

 a degree that wherever found in the Eastport region, specimens can 

 at once be located as belonging to this series. For convenience in 

 description I have assumed that the series is a genus, and the different 

 expressions of the type are different species; but also for convenience 

 I have not described more specimens. 



The form caUed Streptotrochus carinatus (pi. 50, fig. 8) is nearer to the 

 type described by Lindstrom as Trochus incisus than the others; but 

 our species Streptotrochus sulcatus (fig. 9) represents more nearly the 

 dominant expression of characters presented by the Eastport forms. 

 The other specimens ifiustrated are forms which occasionally appear 

 and seem to be uncrushed forms of the shell. From the appearance 

 of the fossils the shells were evidently quite fragile and have aU 

 suffered more or less by crushing after burial in the mud. The longi- 

 tudinal furrowing of the whorls is almost universal, but it is varyuigly 

 expressed. The outer whorl of almost every specimen shows a trace 

 of the furrow; in many it affects the next to last whorl, and (as in 

 specimen called Streptotrochus sulcatus) the outer four whorls are 

 distinctly sulcated. The sutures between the whorls are more or less 

 deep, depending partly upon the abruptness of the left-hand slope 

 from the main carmation of the whorl, as seen in figure 8. All 

 specimens are more or less strongly marked by concentric lines, and 

 in some cases some of these lines are strengthened to form sfight con- 



1 Amer. Jouni. Sci., ser. 3, vol. 32, July, 1886, p. 58. 



