Klem — Revision of the Palaeozoic Pulae'echinoidea. 41 



1, Melonites crassus Hambach. 



1884. Melonites crassus. Hambach, Trans. St. Louis Acad. 



Sci., vol. 4, p. 548, pi. C, fig. 1. 

 1889. Melonites crassus. Miller, N. Amer. Geol. Pal., 



p. 261. 



1894. Melonites crassus. Keyes, Mo. Geol. Surv., vol. 4, 

 p. 126. 



1895. Melonites crassus. Keyes, Proc. Iowa Acad. Sci., vol. 

 2, p. 182. 



Body large, globose, composed of very thick plates. Inter- 

 ambulacra lanceolate, moderately convex, with five columns 

 of plates each. Ambulacra twice as wide as the interambu- 

 lacra, with a very high ridge in the center of each field. 

 Each plate is perforated by two pores. Surface of the ambu- 

 lacra covered with small spines about ^ inch long, and that of 

 the interambulacra with spines about -^w inch long. From 

 forty-five to sixty-eight may be counted to each of the larger 

 interambulacral plates. 



Geological formation and locality : Lower St. Louis 

 Limestone, St. Louis, Mo. 



2. Melonites dispar Fischer. 



1848. Palaechinus dispar. Fischer, Bull. Soc. Imp. Mos- 

 cow, T. 21, p. 243, pi. 3, figs. 4 a-d. 

 1862. Falaechinus dispar. Dujardin et Hupe, Echino- 



dermes, p. 464. 

 1874. Melonites dispar. Loven, Kongl. Svens. Vetens. Akad. 

 Handl., Bd. 11, no. 7, p. 42. 

 Body spherical, convex. Pores piercing the ambulacral 

 plates unequal, one being larger than the other. Tubercles 

 very small and few. 



Geological formation and locality : Carboniferous Lime- 

 stone, Ratofka, Moscow, Russia. 



3. Melonites irregularis Hambach. 



1884. Melonites irregrdaris. Hambach, Trans. St. Louis 

 Acad. Sci., vol. 4, p. 549, pi. C, fig. 2. 



