4 BULLETIN 74, UNITED STATES NATIONAL MUSEUM. 



on the specimens at hand beinfj broken; one shows distinct traces of having been 

 regenerated. They reacli a very considerable lengtli, more than three times tlie 

 liorizontal diameter of tlie test (Clark) ; they are cylindrical, scarcely tapering at 

 all toward the point (Plate 1). Sometimes they show faint longitudinal ridges, 

 which are, however, always quite smooth. The actinal radioles are somewhat 

 flattened and widened (more so in the large specimen), more or less fluted toward 

 the point, but not serrate on the edges; they are slightly curved (Plate 15, figs. 

 1-2 and 7). ' 



The secondary spines are flat and pointed, appressed to the test. Those around 

 the radioles are the largest, about 6 mm. long, the following about half that length, 

 the remainder on the inner part of the interambulacral plates onl\- about 1 mm. 

 long. The primary ambulacral spines are scarcely 3 mm. long, flattened and pointed 

 like the otliers; the inner ambulacral spines are only about 0.5 mm. long. The 

 spines on the apical system are likewise very small, the inner circlet of spines 

 around the anal opening being somewhat larger. "Ampullae" are not found. The 

 spines of the peristome, as usual, are somewhat curved. 



The spicules are of the usual type. The actinal tubefeet are provided with a 

 well-developed sucking disk. In the abactinal tubefeet no sucking disk is developed. 

 In tlie tubefeet on the peristome the disk and the spicules below it are more com- 

 plicated, irregular, spinous plates. 



The pedicellarise, as stated in the Ingolf Echinoidea," are in general similar to 

 tliose of the genus Cidans. The large globiferous pedicellaria? (Plate 17, figs. 12, 

 13) have the valves terminating in a powerful end tooth above the large round open- 

 ing; the stalk has no limb of freely projecting rods. The small globiferous pedi- 

 cellariffi have only a very inconspicuous end tooth; the opening is very large, 

 reaching nearly to the basal part (Plate 16, figs. 4, 10). They occur of different 

 sizes, and the larger cannot always be distinguished with certainty from the triden- 

 tate pedicellariie (Plate 16, fig. 5). These latter (Plate 16, figs. 3, 7, 8, 13; Plate 17, 

 fig. 7) are long and slender (up to 1.5 mm. length of head), the valves joining along 

 their edges in tlieir whole length; the larger ones are rather strongly spinous at the 

 upper end of tlie aj^ophysis, and the blade is filled with irregular meshwork. The 

 edges are thick, irregularly spinous. 



The color is as described by Clark; it ought only be remarked that in the larger 

 specimen also the abactinal system is almost white. 



According to Clark, the species is as yet known only from off the north- 

 western coast of Cuba and from off Barbados, in depths of 125-205 fathoms {Blake; 

 Albatross). I cannot give any additional information on this point. 



That the sjjecies has been confounded with Ilistocidaris {Porocidaris) shairei-i 

 is certain, since the type-specimen was found thus labeled in the British Museum, 

 as stated in the /nr/o// Echinoidea." Whether Agassiz has confounded it with His- 

 tocidaris sharreri, 1 ilo not know; but until it has been definitely proved to which 

 species the specimen of ''Porocidaris sharreri," which was mentioned in the Blake 

 Echini on page 13, as being " of a light greenish-pink color when alive, the 

 spines white with a delicate brownish-pink base," really belongs, I would rather 



a Pt. 1, p. 22. 



