SOME WEST INDIAN ECHINOIDS. 15 



The secondary spines do not present any difFerences. ■AinpuUte" are found in 

 both the typical form and the variety, at least on some of tlie spines of the abactinal 

 system: whether on all of them cannot be decided from the material at hand. 



Certain of the pedicellaria; aflord a rather good distinguishing ciiaracter, 

 namely, the small globiferous. In the variety they have the valves distinctly con- 

 stricted toward the large opening, which is generally not the case in the typical 

 form (Plate 17, figs. 2, 10); however, similar shapes may be met with occasionally 

 in the tj'pical form. In the variety, moreover, the small globiferous {jediccllariae 

 vary considerably in size, the larger ones being very like tridentate pedicellariae 

 (Plate 17, fig. 3), as is also the case in Calocidans micans. Avery curious instance 

 of a small globiferous pedicellaria with two heads was found in the typical form of 

 this species (Plate 17, fig. 9). The large globiferous and the tridentate pedicellarite 

 (Plate 17, figs. 5, 11) are alike in both forms. The same holds good for the spicules. 

 In the Hawaiian and other Pacific Echini, the Cidaridse," Agassiz and Clark 

 give in Plate 12a, figures 1-5, a series of illustrations showing "the great diversity 

 in the large globiferous pedicellarise in Cidaris ahyssicola," on account of which it 

 is deemed to be "unwise to lay any stress on their form as a systematic character" 

 (p. 7). I may reply to this: First, that the figures probably all represent "small" 

 globiferous pedicellariaj, not those of the large form. Perhaps figure 1 represents 

 a large one, though the small gland cavity decidedly points toward its being a 

 "small" globiferous pedicellaria. Next I think that even though the small globi- 

 ferous pedicellariaB are very variable — I quite agree with Agassiz and Clark that 

 they really are — the peculiar form with the constricted valves may be very useful 

 as a specific character; judging from the figures 3-5 in the plate cited of Agassiz 

 and Clark's work I, would even suggest that the specimen from which these pedicel- 

 lariae were taken was one belonging to the variety teretispina. 



Regarding the color it can only be stated that the two specimens at hand of the 

 typical form are quite white, the specimens of the variety more or less brownish. 

 Whether they are differently colored in life must remain undecided for the present. 

 It seems very probable that it is this variety upon which Clark has based his 

 description of C. ahyssicola.'' The expression "median ambulacral area * * * 

 almost wholly covered with small tubercles"' certainly agrees best with the variety. 

 Also the fact pointed out by Clark that "the uppermost coronal plates do not 

 carry primaries, and even the second ones may lack a well-developed spine," decid- 

 edly agrees better with the variety than with the typical form, 'in which latter 

 some of the upper plates have well-developed radioles in both the specimens at 

 hand. Finally, the figures in the Revision of the Echini (Plate 1 , figs. 1-4) to which 

 Clark refers,' seem to represent the variety; figure 1 alone with its thick radioles 

 seems to represent the typical form, though tlie radioles are not so ilistinctly fusi- 

 form. But in any case the original description gives some of the distinguishing 

 characters— the radioles and the ambulacra— so excellently that it seems beyond 

 question that it is the form figured here in Plate 7, figures 1-2, and Plate cS, whicli 

 must be regarded as the typical Cidaris ahyssicola. Regarding the variety described 

 above, I am inclined to think that it will ultimately prove to be a distinct species, 



'1 .Mem. Mus. Comp. Zoo!., vol. 24, 1907. ^The Cidaridse, p. 208. 



