34 



Group V. Planulati, Waagen, non Buch. {Coronarii, Buck, et 

 auctorum, pars.) 



Subgenus Peeisphinctes, Waagen. — "Geognostich-Pal<eontologischeBeitrage," von 

 Dr. E. W. Benecke. Munchen : 1869. Band 2, jj. 248. 



Ammonites Skidegatensis. (N. Sp.) 



Plate VII. Adult and type. Plate IX., figure 1 : An immature, but perfect speci- 

 men, supposed to belong to the same species. 



Fig. 4. 



Fjg. 4i.—A. Skidegatewils . — Outline of aperture of the specimen| represented at 



Plate VII. 



Shell compoi^ed of many roiiiuled whorls; umbilicus much moi-e than 

 half the entire diameter ; surface regularly eostate ; ribs acute and separa- 

 ted by broad convex grooves, alternately bifurcating and simple. Volu- 

 tions sharply coronated above Jind below. 



The sides of the inner whorls are fully exposed; the umbilicus is 

 accordingly very Avide, it is also rather shallow externally, but is much 

 deeper (apparently) near the centre. Measuring from suture to suture, 

 the inner Avhorls (collectively) make up rather more than half of the 

 entire diameter. Onl}^ the two outer volutions are visible in the largest 

 specimen, the rest being covered b}^ hard and tenacious shale, which 

 could not be removed except at the risk of spoiling the fossil. As seen 

 transversel}', the outer whorl is raised at the sides, and slightly com- 

 pressed at the periphery. Its base is shallowly and concavely emargi- 

 raate by the encroachment of the preceding volution. The aperture is 

 about one-third wider than high ; its greatest breadth being a little 

 below the middle. 



