262 Trans. Acad. Sd. of St. Louis. 



maguifying orlass- Upon those specimens from which the 

 shell substance has been removed, the impressions of the 

 vascular sinuses are well developed. The internal structure 

 of the shell is as has been described in the definition of the 

 genus. 



None of the type specimens of this species are perfectly 

 preserved so that the dimensions given below are approximate 

 rather than exact. The largest specimen has a width of 

 29 mm., an approximate length of 42 mm., and a thickness 

 of 26 mm. A smaller specimen has a width of 24 mm., a 

 length of 36 mm., and a thickness of 22 mm. The average 

 rostral angle as determined from the eleven specimens ex- 

 aximed which are complete enough for measurement, is 73.5°. 



Locality. The cotypes of the species (Pal. Coll. Walker 

 Museum No. 7800; 13 specimens), are from a dove-colored, 

 Kinderhook limestone occurring on the South Fabius river, 

 in the south-eastern corner of Knox County, Missouri. 



Paraphorhynchus striatocostatum (M. & W.). 



PI. l,f. 6-11. 



1868. Rhynchonella Missouriensis , Meek and Worthen, 



Geol. Surv. 111., vol. 3, p. 450, pi. 14, figs. 7a-d. 

 1868. RhyncJtoneUa striatocostata, Meek and Worthen, 



Geol. Surv. 111., vol. 3, p. 452. 

 1895. Pugnax striato-costata, Hall and Clarke, Pal. N. 



Y., vol. 8, pt. 2, p. 204. 

 1895. Pugnax missouriensis, Hall and Clarke, Pal. N. Y., 



vol. 8, pt. 2, pi. 60, figs. 33-34. 



1897. Pugnax striaticostata, Schuchert, Synop. Am. Foss. 

 Brach., p. 336 (in part). 



1898. Pugnax striaticostata, Weller, Bibliog. Index N. A. 

 Carb. Inv. p. 517-518, (in part). 



1900. Pugnax striaticostata, Weller, Ann. Rep. la. Geol. 

 Surv., vol. 10, p. 76. 



1901. Pugnax striaticostata, Weller, Trans. St. Louis 

 Acad. Sci., vol. 11, p. 154, pi. 13, figs. 14-16. 



Shell about as long as wide but varying a little in either 

 way; broadest at about the middle. The pedicle valve shal- 



