Il6 ECHINOIDEA. I. 



tooth; the outer corners of the basal part are strongly produced in a wing-shaped manner, and the 

 holes in the corners are most freqiiently somewhat lengthened. No neck or perhaps a short one; as 

 I have only had dried specimens for examination, I have not been able to decide this faet witli cer- 

 tainty; the stalk compact. In the tridentate pedicellariæ (PI. XIX. Fig. 39) the blade is rather broad 

 with a strong, somewhat thorny net of meshes at the bottom. The edge is strongly indented, espe- 

 cially in the outer half, where the valves join; in the lower half they are apart, but not very miich. 

 The ophicephalous pedicellariæ have an almost straight edge, whicli is otherwise finely serrate as 

 usual; the teeth, as is often the case, continue down the npper ends of the apophysis. The triphyllous 

 pedicellariæ (PI. XIX. Fig. 29) are very j^ecnliar, the upper end of tlie apophysis forming a cover-plate, 

 from which digitate projections pass over the blade, which is curved strongly inward in the middle. 

 The edge smooth as usual. The spicules are bihamate, very few in number. 



Ez'cchiinis rarititbcrculatns Bell is by Far q uh ar (145) taken to be young specimens of E.chlo- 

 rotiais. It is certaiu that it is very similar to chlorofiais, but I cannot regard it as proved that it is 

 synonymous with this species, as the tridentate pedicellariæ (PL XIX. Fig. 7) show a considerable dif- 

 ference from those of chloroticits. They have no coarse indentations in the edge, which is almost 

 straight and very slightly serrate, only at the lowermost part there are a few larger indentations; the 

 net of meshes in the bottom is slight,' not thorny. The valves join through almost their whole 

 length. — Perhaps similar pedicellariæ may be found in clilorotiais together with the form described 

 above; in my specimens, however, I have not been able to find such. For the present I must then 

 regard rarititbcrculatns as a separate species. — Tlie globiferous and ophicephalous pedicellariæ are 

 quite as those of clitoroticus ^ the triphyllous ones I have not seen. — Of Evcch. australier Woods I 

 kiiow nothing. 



Agassiz (Rev. of Ech. p. 502) tliinks Evechimis to be closely allied to Tripnciistcs [Hipponoc); 

 that there is no nearer relation at all between these two genera is seen with all desirable distinctness 

 from the facts given above. The unpaired lateral tooth on the globiferous pedicellariæ draws tlie 

 attention to Pscttdechinus albociiictus\ but the naked buccal membrane in the latter and the faet that 

 a primary tiibercle is here found on all the ambulacral piates, do not indicate a very near relation 

 between the two forms. A quite similar form of globiferous pedicellariæ is found in .Strongyloccn- 

 trotus ■ tubcrculatus and closely allied species, and these, no doubt, are its nearest relations. A more 

 thorough inquiring into this question must, however, be put off, until these species are treated. 



In «Cat. rais.v the species variolaris Lamk., paucitubcrculafus Blainv., and cldoroticus Val. are 

 eniirnerated under the genus Hcliocidaris. — For the first of these species the older name of Sfoiuo- 

 pncustcs must be used; according to Agassiz (Rev. of Ech.) pajtcitjibcrculatus is synonymous with 

 this. As far as I can see, cldoroticus must then be the type of the genus Hcliocidaris; the name of 

 Evechinus Verr. (1871) must then be dropped as being a much younger one, and I cannot but wonder, 

 why Agassiz, who otherwise takes great care to reestablish the oldest naraes, has here preferred the 

 name of Evechinus. 



To the genus Sphærechinns Desor the species graiuilaris (Lamk.), roscus Russo, australier A. Ag., 

 and pidcherrimus (Barn.) are referred; of these I have had no occasion to examine Sph. roseics, but 



