Weno and Pawpaw Formations 97 



of the ray; and P. obtusus Forbes (Upper Chalk) is stated to have 18 

 marginal plates, the superior ones punctate and the two sets alternating. 



I (type) II 



R (average of five) 23.5 mm. 15.9 mm. 



r (average of five) 14.8 mm. 9.9 mm. 



R/r 1.58 1.6 



METOPASTER HORTENSAE Adkins and Winton 

 PI. 7, fig. 6 



1920: Metopaster hortensae Adkins and Winton, Univ. Texas Bull. 1845, p. 46, pi. 10. 



figs. 2-4. 



1920: Metopaster sp. Winton and Adkins, Univ. Texas Bull. 1931, p. 69. 

 1920: Metopaster hortensae Winton and Adkins, ibid., p. 21. 



This rare species, which characterizes the basal Pawpaw clay, has very 

 tuberculated and spiny plates. The marginals are covered with closely 

 set, low, rounded tubercles, and at places have adherent clumps of small 

 thick spines. 



One row of ambulacral pore plates is shown on the type individual. 

 This has two rows of oblique pores, indicating four rows of tube-feet per 

 groove. 



As already stated, there are six paired supero- and infero-marginals in 

 addition to the terminal unpaired supero-marginal plate, totalling eight 

 supero-marginals and six infero-marginals. 



The terminal marginal plate is similar to that of Mitraster, which differs 

 from the Texas form in its cycloid contour and in the shape and ornamen- 

 tation of its marginal plates. 



COMPTONIA WINTONI n. tp 



PI. 7, figs. 4-5 

 1920: Comptonia sp. Adkins and Winton, Univ. Texas Bull. 1945, p. 49, pi. 10, fig. 1. 



MEASUREMENTS: 



Major radius, about 24 mm. 



Minor radius (average) 6 mm. 



DESCRIPTION: Disk flat although somewhat collapsed in the type. 

 Rays elongate, tapering, incomplete in the type; probably the ratio R:r is 

 about 4:1. Minor radius about 6 mm. in the type. Supero-marginal and 

 infero-marginal plates numerous, usually paired, disk relatively small and 



