386 REPORT ON THE STATE CABINET. 



MODIOLOPSIS RECTUS, N. S. 

 PLATE XIV, FIGS. 4, 5. 



Shell elongate, narrow, moderately convex, beaks subanterior; hinge- 

 line long and straight ; the greatest width of the shell is at the 

 posterior end of the cardinal line, narrowed equally above and 

 below towards the posterior extremity. The anterior muscular 

 impressions large and strongly defined. The casts show that there 

 has been one strong subtriangular tooth beneath the beak of the 

 right valve, with one or two smaller ones, with corresponding pits, 

 in the opposite valves. The lateral teeth are very slender. The 

 surface has been marked by concentric striae, and a few strong undu- 

 lations which are preserved in the casts. The length is about one 

 inch with the greatest breadth half an inch. 



This species resembles Ilodiolojms {Tellinomya) machcsraformis of the 

 Clinton group of New York, from which it differs in having the beaks 

 more nearly anterior and in being less narrowed posteriorly ; while the 

 greatest width is at the posterior extremity of the hinge-line, instead of 

 at the beaks. 



Some specimens, which are scarcely specifically distinct from those 

 described, have proportionally a somewhat greater width, but in other 

 respects are identical. 



Formation and Locality. — In limestone of the Niagara group, at Wau- 

 kesha and Racine, Wisconsin, and at Bridgeport, Illinois. 



MoDIOLOPSIS SDBALATUS, HaLL. 

 Modiolopsis subalatus, Hall. Pateontology N. Y., II, pp. 84, 285, Plates xxvii, lix. 



Some specimens from Racine, Wisconsin, and Bridgeport, Illinois, are 

 apparently identical with this species of the Niagara group of New York. 

 The specimens are casts and more or less crushed and imperfect, 



GENUS AMPHICGELIA, n. g. 



The Acephala present great difficulties in the way of satisfactory 

 generic reference ; and it is often scarcely possible to arrive at certainty 

 with regard to their true relations. 



A single species from Wisconsin, which is somewhat numerous in 

 individuals, has the general exterior aspect of the more elevated forms 



