NO. 6 NEW AMERICAN EDRIOASTEROIDEA BASSLER II 



is in reality, according to its genotype, H. parasiticus, a Carneyella 

 with broad, short, straight ambulacra and with squamose imbricating 

 overlapping plates. The genus is the most prolific of all the edrio- 

 asteroids so far known. New figures of the genotype and of several 

 previously known species referred to other genera, as well as illus- 

 trations of Barrande's species (pi. 7, figs. 2-6), are introduced here 

 in addition to the description of several new species. 



HEMICYSTITES PARASITICUS Hall, 1852 

 Plate 4, figs. 5, 6 



The original figure is diagrammatic, as it is based upon a some- 

 what crushed and broken specimen, but comparison of the type with 

 a complete example from the same horizon and locality shows the 

 generic as well as specific features of the species. The ambulacra are 

 short, broad, and straight, with numbers i and 5, between which the 

 anal pyramid is located, diverging at a wider angle than the rest. 

 The interambulacral plates are elongate, polygonal, imbricating, and 

 the marginal rows of plates, six or seven in number, increase in size 

 from a row of minute ones at the edge to a row composed of large 

 plates encircling the ambulacra. The anal area is large, consisting 

 of six or seven elongate triangular plates meeting in pyramid form. 



Occurrence. — Clinton (Rochester shale), Lockport, New York. 



Plesiotype.—U.S.^M. no. S-3183. 



HEMICYSTITES (LEBETODISCUS) MULTIBRACHIATUS (Raymond), 1915 

 Plate 4, figs. 3, 4 



The holotype of this species (fig. 3) is surely an abnormal indi- 

 vidual in which the original five ambulacra have been increased to 

 eight by branching of numbers i, 2, and 4. The same locality affords 

 very similar specimens with the normal five ambulacra (fig. 4), for 

 which reason such specimens are included under the same name 

 irrespective of the number of arms in the type. H. multibrac hiatus 

 can be recognized by its short, widely separated straight ambulacra 

 with seven to eight covering plates to a row, surrounded by a broad 

 band of rather nodose, imbricating plates. 



Occurrence. — Trenton (Hull formation), Kirkfield, Ontario. 



Plesiotype.— V.S.N. M. no. S-3894. 



HEMICYSTITES (LEBETODISCUS) CHAPMANI (Raymond), 1915 

 Plate 3, fig. 9 



This very beautiful species is remarkable for the length of the 

 ambulacral areas, which are broad in the oral region and taper gradu- 



