CANADIAN ORGANIC REMAINS. 



Maclurea Logani, Salter. 

 Decade I. Plate I. 



Generic character. — Maclurea, Lesueur. Mollusca Nucleobranchiata. 

 Family Atlantidee? "Shell discoidal, few whorled, reversed* 

 (the apical whorls being brought down to the base and the 

 umbilicus flattened out) ; upper surface convex, deeply perfo- 

 rate instead of raised into a spire ; outer side spirally grooved ; 

 operculum sinistrally sub-spiral, solid, with two internal pro- 

 jections for the attachment of muscles — one of them beneath the 

 nucleus, and very thick and rugose." — Woodward. 



Synonyms. — M. Logani, Salter, in Rep. Brit. Assoc, 1851, Trans. 

 Sections, page 6-3 ; in Murchison's " Siluria," 3rd edit., 1859, 

 page 215, figure 1 (?) and la, operculum. 



Diagnosis. — M. 3| uncias lata, paucisyirata ; anfractibus 4-5 (ultimo 

 in latitudine prcecedentem ter superante), subtus planissimis Icevigatis, 

 et ad latera multistriatis insurer, valde convexis, umbilico parvo. 



This fine species, detected in great plenty by the officers of the 

 Survey in exploring the Ottawa river, was first noticed in Sir R. I. 

 Murchison's paper on the Silurian Rocks of the South-west of Scot- 

 land, in the Quarterly Journal of the Geological Society, vol. vii., 

 1851, page 176, and its name proposed in the British Association 

 Reports for the same year. 



* The reader will please to bear in mind, that though drawn uppermost on the plate 

 (a position which shews the characters best), the flat spiral side of the whorls is really 

 to be considered the base, and the umbilicus the upper side. See Woodward's Manual 

 of Shells, p, 202, where the shell is represented (fig. 106) in its normal position. 



