236. 



were evidently very imperfect, and it appears to have been not possible 

 to give the details of the specific characters. The figures barely show 

 enough to indicate the genus. I have heretofore referred to M. matutina, 

 with doubt, a species found in the Calciferous at the Mingan Islands, and 

 have also thought that I could recognize it in the limestone of the Quebec 

 group at Phillipsburgh. It has now, however, become apparent, from the 

 collections made in Newfoundland, that there are several distinct species, 

 all having nearly the form and proportions indicated by the figures in the 

 work above cited ; but it is, at present, impossible to decide that any one 

 of them is truly M. sordida or M. matutina. I propose, therefore, to 

 describe them all as new, and to leave it for future discoveries to deter- 

 mine whether or not those which occur at the typical locality, in New 

 York, are represented among them. 



In the following descriptions the shell is regarded as being sinistral ; 

 the flat side is thus the spire and the umbilicated side the base. 



Although I think that the genus Ophileta is founded on species of 

 Maclurea, with very slender whorls, I retain it for the present pro- 

 visionally. 



MACLUREA CRENULATA. (N. sp.) 



a b c 



Fig. 222. 

 Fig. 222. Maclurea crenulata. a, base ; 6, front; c, spire. 



Description. Shell hemispherical ; spire flat, of three or four rather 

 slender whorls , outer edge narrowly rounded angular ; umbilicus about 

 one-third the whole width, with a sharp crenulated edge ; inner side of 

 the whorls, in the umbilicus flat and nearly vertical ; all the whorls 

 exposed in a spiral staircase form to the apex. The base forms an 

 irregular hemisphere, highest at the aperture. 



Surface finely striated, and usually with some rugose lines of growth. 



These latter are sometimes absent, and the shell has then a smooth 

 aspect. 



