404 THE CANADIAN NATURALIST. [Vol. viii. 



variety of the same species. It is not easy to see how M. per- 

 tenuis can be distinguished from M. minima, Sowerby, of the 

 European Lias, as figured and described in the Mineral Con- 

 chology and by Goldfuss. 



11. Grammatodon inornatus, Meek & Hayden. Utasyouco 

 River, two single valves. Apparently very near to Area Lineata 

 Goldfuss, from the Lias of Germany. 



12. Grammatodon (? ) Iltasyoucoensis, N. Sp. — Shell mode- 

 rately convex, but slightly depressed near the middle below ; 

 very inequilateral ; anterior end short, narrow and obtusely 

 pointed ; posterior end elongated, widening gradually both above 

 and below ; truncated almost squarely at its extremity. Hinge 

 line straight, ascending gradually behind the beaks, and sloping 

 downwards rather abruptly in front of them. Beaks broad, 

 depressed, curved inwards and forwards, situated very near to 

 the anterior end, but not quite terminal. Right valve (the only 

 one known) with indications of one or two elongated, linear 

 posterior teeth, placed parallel to the hinge line, and of at least 

 three obliquely transverse anterior teeth. Surface marked with, 

 close-set, crowded and extremely fine, radiating striae, which are 

 scarcely visible to the naked eye, and which become almost 

 obsolete on the ill-defined posterior area. 



Utasyouco River, a single specimen of the right valve, with 

 the lower half of the posterior end broken away. The pallial 

 line and muscular impressions are not visible, and the hinge cha- 

 racters are imperfectly shown, so that it is doubtful whether this 

 shell is a Grammatodon or a true Maerodon. 



13. Cucullcea (?) Sp. TJndt. — A small, rather ventricose, sub- 

 rhomboidal species, with prominent, nearly central, incurved 

 beaks. An obtuse keel runs from the beaks to the base, and 

 separates an obliquely flattened posterior area from the main 

 body of the shell. The surface is marked by close-set, raised 

 striatums, which are crossed by rather more distant, radiating 

 lines. 



14. Toldia (or Corbis) Sp. Undt. — A single valve of a small 

 shell from the Utasyouco River, with no vestiges of the hinge 

 teeth or of any of the markings of the interior remaining. The 

 outline of the specimen is remarkably like that of Nucula spe- 

 ciosa, Munster, from the Muschelkalk of Germany, which is 

 probably a Yoldia or Portlandia, but it is also almost equally 

 similar in its shape to Corbis uniformis, Phillips, from the 



