l6 ECHIXOIDEA. I. 



to the same genus (Leiocidaris) as C. vcrticillata. In this species the thorns are often placed in circles 

 in a somewhat similar way as in C. verticillata. 



Especially the large globiferous pedicellarise are of importance in the classification, the blade 

 and partly also the stalk offering a great variety of forms. Also the length of the stalk is very 

 different; this fact, however, has to be used with great caution, at it is very varying. Doderlein 

 seems to put no small weight upon it. Also the small globiferous pedicellarise are of rather great 

 importance; more important, however, are the tridentate ones, which in a single genus, Porocidaris, 

 are two-valved. In this genus (and perhaps in the genus Histocidaris} globiferous pedicellarise seem 

 to be quite wanting; on the other hand tridentate pedicellarise are wanting in several other species - 

 but perhaps not constantly. That the globiferous or tridentate pedicellarise may sometimes be want- 

 ing, is mentioned by Doderlein as an objection to their being used in the classification. I cannot 

 see, however, that this objection is sound; a corresponding fact would be, if we were to give up using 

 the teeth of the mammals as systematic characters, because now one, now another kind, or even 

 sometimes all of them are wanting. 



When we now look over the Cidarids, and place together the species with similarly constructed 

 pedicellarise, we shall get a grouping rather differing from all hitherto given classifications. 



Dorocidaris papillata: the globiferous pedicellarise have a powerful hook at the point, above 

 the large, somewhat lenghtened, not terminal opening; small pedicellarise of the same form; the triden- 

 tate ones simple (PI. IX, Figs. 7, 25). Quite similar pedicellarise are found in Dorocidaris Blakci A. Ag. 

 (PI. IX, Fig. 16), which is accordingly a genuine Dorocidaris. On the other hand the following species 

 that have been referred to Dorocidaris: D.Bartletti Ag., bracteata Ag., and Rcini Doderl. differ widely 

 from this genus, and are moreover so different from each other that they must be referred to three 

 different genera. 



D. Bartlctti: the globiferous pedicellarise have a long powerful hook at the point The opening 

 is exceedingly small, as a fine pore, surrounded by small teeth; it is placed rather far from the point. 

 (PI. X, Figs. 23, 30). The stalk is most frequently provided with a limb of freely projecting calcareous 

 ridges. The small pedicellarise are of the same structure, only the opening is larger; tridentate pedi- 

 cellarise simple. There can be no doubt but that this species must form a separate genus; I propose 

 the name of Tretocidaris 1 ). To this genus must further be referred the two following new species, 

 which I found in British Museum, both under the name of Dorocidaris papillata. 



Tretocidaris annulata n. sp. The globiferous pedicellarise differ somewhat from those of T. 

 Bartlctti the inside of the blade being provided with some dentate transverse ridges and crests forming 

 a coarse, irregular reticulation; at the upper end of the apophysis the margin of the blade is somewhat 

 widened, highly fenestrated in a reticulate way, and bent a little outward (PI. X, Figs. 22, 31). The stalk 

 (PI. IX, Fig. 4) and the other pedicellarise as in T. Bartletti. The spines are finely annuiated with 

 brown rings, the upper spines have powerful thorns especially on the side turned up; they are tapering, 

 about one time and a half as long as the diameter of the test; the actinal spines were wanting in 

 the specimen. There is a rather deep, naked furrow along the median line of the interambulacral 

 areas, and it continues between the plates outward to where the scrobicular areas join each other. 



') TpijTi'tg = bored. 



