J2 NEW YORK STATE MUSEUM 



Dinobolus canadensis (Billings) 

 Plate 24., figures 13 and 14 



The Watertown limestone of the Black River group at Water- 

 town, N. Y., has furnished us a well-preserved mold of the brachial 

 valve of a Dinobolus that is identical with D. canadensis 

 (Billings). It possesses the characteristic subpentagonal outline 

 and oblong platform with anteriorly produced septum. The cres- 

 cents are but faintly developed. The specimen is smaller than the 

 mature types figured by Billings, though agreeing in that particular 

 with one of his figures. On account of this smaller size, a com- 

 parison with D. (?) parvus (Whitfield) from the Galena 

 of Wisconsin and Minnesota might suggest itself, but that form as. 

 figured by Schuchert (Paleontology of Minnesota, v. 3, pt 1, p. 356. 

 1895) has a broader and more circular outline and lacks the distinct 

 crescents. D. canadensis, according to Billings, occurs 

 abundantly in the Black River beds at Pauquette Rapids in lower 

 Canada, but has not been as yet recorded from the Black River 

 beds of New York. 



Protospira minuta nov. 

 Plate 25, figures 1 and 2 



Description. Shell minute, spiral, turreted, slender, solid, con- 

 sisting of about five or six volutions. Whorls gently convex, 

 sutures moderately deep ; body whorl not larger than the others. 

 Aperture crescent-shaped, through a lobelike extended outer lip. 

 Inner lip formed by the penultimate volution. Surface with few 

 slightly sigmoidal growth-lines, which are deepest in the sutural 

 grooves. Length of shell 6.5 mm. 



. Horizon and locality. Hoyt (Ozarkian) limestone, Hoyt quarry, 

 town of Greenfield, Saratoga county, N. Y. 



Remarks. This remarkable, small gastropod was found by the 

 author in one specimen in the oolitic limestone of the Hoyt quarry. 

 It is there associated with other peculiar gastropods, namely, 

 Triblidium cornutaforme (Walcott), Pelagiella 

 minutissima and hoyti (Walcott) and Matherella 

 saratogensis (Walcott). It is needless to say that all these 

 Cambric gastropods are minute and extremely primitive forms. 

 Yet they exhibit already the different types of convolution observed 

 in their descendants, Pelagiella being coiled in one plane, Matherella 

 in a low, broad, sinistral spiral, and Protospira in a high, turreted, 

 dextral spiral. 



