142 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Archaeopneustes. 



Gregory, 1892. Quart. Journ. Geol. Soc. London, 48, p. 163. 

 Type, Palaeopneustes hystrix A. Agassiz, 1880. Bull. M. C. Z., 8, p. 82. 



This genus was proposed by Gregory for Palaeopneustes hystrix and certain 

 West Indian fossil species. The characters he selected, however, (petal length 

 and form, and position of the mouth) are most unfortunate and he quite over- 

 looked the really important character (tuberculation of actinal ambulacra) 

 pointed out by Koehler in 1914. Gregory quite reversed the facts as to the 

 position of the mouth because he relied on A. Agassiz's figure (1883. Blake 

 Ech., pi. xxi, fig. 11) of a very young cristatus, whereas the figure of the adult 

 given by Mr. Agassiz (1874. Hassler Ech., pi. iv, fig. 3) with his original full 

 description shows clearly the very anterior position of the mouth. Petal length 

 and form vary somewhat with age and I fail to find even specific differences 

 therein. Besides the West Indian type species two Oriental forms seem to 

 belong here. I find no ophicephalous pedicellariae present in the West Indian 

 species but they occur in both the others. Tridentate pedicellariae, rostrate 

 and triphyllous all occur in great numbers but the rostrate are not always 

 clearly separable from the broad tridentate. Calcareous particles in the pedi- 

 cels are scattered knobbed rods (PL 145, fig. 20) which in the penicillate pedicels 

 about the mouth become more or less slender perforated plates. 



Key to the Species of Archaeopneustes. 



Test of moderate height, v. d. not exceeding .60 length. 



Mouth distinctly anterior; anterior margin of labium only about .30-.35 test-length 



from anterior margin of test; test low, v. d. not exceeding half test-length . . . hystrix. 

 Mouth less anterior; anterior margin of labium about .40 test-length from anterior 



margin of test; v. d., .50-.58 test-length niasicxu. 



Test high; v. d. .61-73 test-length; anterior margin of labium about .40 test-length from 



anterior margin of test hemingi. 



Archaeopneustes hystrix. 



Palaeopneustes hystrix A. Agassiz, 1880. Bull. M. C. Z., 8, p. 82. 



Archaeopneustes hystrix Gregory, 1892. Quart. Journ. Geol. Soc. London, 48, p. 168. 



Plate 145, figs. 20-26. 



The pedicellariae alone remain to be described of this West Indian species. 

 It is rather remarkable that I found no ophicephalous and no globiferous pedi- 

 cellariae, though the latter are not known in the genus. The triphyllous (PL 



