KCHINOIDKA. II. 



35 



The petals are considerably shorter and less developed than in pusillus, the number of pores 

 being almost double in the latter species, when comparing specimens of a corresponding size of 

 the two species, as is easily seen from the table given and from a comparison of figures 5 and 31. 

 PI. XII. The pores are somewhat smaller than in pusillus (those of the inner series smaller than 

 those of the outer series), with no distinct glassy protuberance between the pores of each pair; the 

 pairs are also more oblique and more distant than in pusillus. It is further a conspicuous feature 

 that the petals are converging outwards, the two series of each petal being more distant at the inner 

 end - likewise a very conspicuous difference from pusillus. (Comp. Figs. 5 and 31. PI. XII). (In one 

 specimen, S-s""" in length, the petals are quite irregular, consisting of some few, scattered pairs of 

 pores; only the right posterior petal is almost normal. Also the genital and ocular pores are quite 

 abnormally placed in this specimen). There is further a considerable difference from pusillus in the 

 number of the small ambulacral pores; on the actinal side they are arranged only in a single series 

 along each horizontal suture, except in the two inner pairs of sets, in which they form, more or less 

 distinctly, two series. This is the case also 

 in the largest specimens seen, g mm in length. 

 On the abactinal side they are arranged as 

 in pitsillus. only I have been unable to dis- 

 cern with certainty such pores within the 

 petals. The genital pores I have found de- 

 veloped in a specimen only 2 - 8 mm in length; 

 on the other hand I have also seen a speci- 

 men of 4 mm length with as yet no traces of 

 genital openings. Large genital papilla? may 

 be developed. 



The tuberculation is somewhat less 

 close than in pusillus, and the glassy protube- 

 rances among the tubercles are likewise less numerous, but, on the other hand, they are more promi- 

 nent being considerably higher than the primary tubercles; they are striated, ending in a knob, almost 

 like the mamelou of a tubercle, which is, however, not perforated, since no spine is articulated to it. 

 (PI. XII. Fig. 14.) This seems, however, to be a rather inconstant feature, and in any case it is very 

 indistinct in less well preserved specimens. 



The supporting ridges of the interior of the test (PI. XII. Fig. 3) are less strongly developed 

 than in pusillus. not proceeding to the auricles as in the latter species, but ending some way out- 

 side the auricles, which are also more distant from the edge of the peristome than in pusillus. (Comp. 

 PI. XII. Fig. 3 and 29.) It will be seen that the figure given in Revision of Echini PI. XIII. 7 is 

 much more in accordance with the figure given here of grandiporus than with that of pusillus. though 

 not quite agreeing with this figure either. The depressions along the ambulacral sutures are much 

 less prominent than in pusillus. — In accordance with the place of the auricles the dental apparatus 

 is considerably larger than in pusillus, as shown in Fig. 2, which represents the dental apparatus of 

 specimens of j mm length of pusillus and grandiporus. Both agree in having it unequally developed 



5* 



Fig. 2. Dental apparatus of Echinocyamus, 7mm. 

 a Ech. grandiporus, b Ecli. pusillus. 17/1. 



