262 Trans. Acad. Sci. of St. Louis. 
magnifying glass. 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 26mm. A smaller specimen has a width of 24 mm., a 
length of 36 mm., anda 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.). 
Pl. 1,f. 6-11. 
1868. Rhynchonella Missouriensis, Meek and Worthen, 
Geol. Surv. Ill., vol. 3, p. 450, pl. 14, figs. 7a—d. 
1868. Rhynchonella striatocostata, Meek and Worthen, 
Geol. Surv. Ill., vol. 8, 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, pl. 60, figs. 33-384. 
1897. Pugnasx striaticostata, Schuchert, Pyne. Am. Foss. 
Brach., p. 336 (in part). 
1898. Pusiae striaticostata, Weller, Bibliog. Index N. A. 
Carb. Inv. p. 517-518, (in part). 
1900. Pugnax striaticostata, Weller, Ann. Rep. Ia. Geol. 
Survy., vol. 10, p. 76. | 
1901. Pugnax striaticostata, Weller, Trans. St. Louis 
Acad. Sci., vol. 11, p. 154, pl. 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- 
