ECHINOIDEA. I. 17 



There are 7 plates in the interambnlacral areas. In the anibulacral area there is a httle tubercle 



alternately between each two primary tubercles 



Oo 

 ©o 



, as in Porocidaris purpurata. The colour of the 



test is redbrown, and therefore the white, naked furrow of the interambnlacral areas is especially con- 

 spicuous. — Locality: The West Indies (no nearer information). Should this species perhaps be 

 Gray's Cidaris amiiilatal 



Tretocidaris spinosa n. sp. The globiferous pedicellariLc have no such reticulation as those 

 of T. anindata^ and differ from those of T. Bartlrtti by the sides forming an almost straight line from 

 the basal surface to the opening. (PL X, Fig.s. 10, 11). The small globiferous pedicellarise as in the 

 two other species (PI. X, Fig. 16). On the stalk no distinct, freely projecting calcareous ridges are 

 seen, only a marked swelling. (It is, however, possible that the limb of the stalk is found on other 

 specimens; in the two other species it was not found either in all the large globiferous pedicellarise); 

 tridentate pedicellarise were not found. The spines closely grooved, rather finely thorned, widened at 

 the point, of the same length as the diameter of the test. The actinal spines smooth, not serrated, their 

 points not widened. The small spines are strongly redbrown. There is a naked median line in the 

 interambulacral area, but it is only little conspicuous. 9 plates in the interambnlacral area; thus the 

 large spines are somewhat more numerous than commonh^, which gives to the animal a very charac- 

 teristic appearance. The tubercles in the anibulacral areas as in T. amiulata. Locality : St. Helena (no 

 nearer information). 



i'.Dorocidaris bractcata Ag. The globiferous pedicellarix much lengthened and narrow, with a 

 powerful hook at the end, and a rather small, triangular opening a little below the point (PI. X, 

 Fig. 18); the small pedicellarise of the same structure, tridentate ones simple. This form of pedicel- 

 larise is further found in Phyllacanthusr, ainiuUfcra (Lamk.), PI. X, Fig. 17, and Stcphanocidaris bispi- 

 nosa (Lamk.), and these species will have to be united into one genus, which must keep the name of 

 Sfcpba Hocidaris. 



Dorocidaris Rcini Doderl. The globiferous pedicellarise are of a very peculiar structure; the 

 mouth is placed in the end of the blade, surrounded by well marked teeth on the margin which is bent 

 a little outward. < Schnauzenahnlich vorragend Doderlein says of the blade in this peculiar form 

 of pedicellarite, and it really resembles a snout to some degree. On the stalk a limb of short thorns 

 is found. The small pedicellaria; are of a quite different structure, a well developed end-tooth being 

 found here, and the large mouth situated below the point. This form of pedicellarise is found in a 

 series of species, viz. Cidaris affiuis (PL IX, Figs. 9, 22, 24) (which is in no way synonymous \\A\h Doro- 

 cidaris papillata, as has been commonly supposed), tribuloidcs, galapagcnsis — and, I suppose, also in 

 Dorocidaris panamcnsis Ag. ; at all events this species, to judge by the figure, would seem to be most 

 nearly related to Cidaris affiuis and Rcini; it is scarcely a Dorocidaris. The following species have 

 pedicellarice of the same structure, but are distinguished by having a limb of long, freel\- projecting 

 calcareous ridges on the stalk of the globiferous pedicellarise: Cidaris metularia, Thouarsii (according 

 to Doderlein (116 p. 19) Cidaris Tlioiiarsii has only a short Hmb on the .stalk; the specimens examined 

 by me have long limbs), vcrticillata and baculosa. Further has (according to the statement of Doder- 

 lein) Phyllacantlms iiupcrialis the same kind of pedicellarise (whether a limb is found on the stalk 



The Ingolf-Expedition. IV. i. 3 



