BIIIANG TILL K. SV. VET.-AKAD. IlANDL. BAND 13. AFD. IV. N:0 10. 5 



placed on the adoral slope. Of one of tliese lioUows the /rr/. 7 

 gives a correct representation; in the ficf. 1 they are pnrposely 

 too stronglv marked. 



The interradia enter iuto the peristome, as it appears, 

 each with a single plate. Thiis it is assuredly in the 1, 2, 3, 

 4, and thus also, I believc, in the posterior interradium, 5, 

 which, however, sometimes seeraed dimly to show a trace of 

 a median dividing suture, a dubious trait which I have thouo-ht 

 it rioht to mention. The peristomal plate is followed as iisual 

 bv the double series of interradials. 



The spines are all löst. Their tubercles are of a fair size 

 and present a rather large scrobicule, a crenulated cone, and 

 a perforated mamelon, pg. 8. In the ambulacra there are two 

 lateral rows of primary tiibcrcles, in the interradia likewise, 

 with two middle series, short and alternating, added near the 

 ambitus. The first interradia! tubercle is sub-median and pla- 

 ced on the peristomal slope. The interradial tubercles are but 

 slightly larger thau the ambulacral. 



In the ambulacra as wcU as in the interradia the space 

 between the tubercles is densely crowded with mostly ovoidal, 

 rarely circular, oftener irregular, occasionally conlluent protu- 

 berances of a striking aspect, Jig. 6", 7, 6', 5*, 10. At the peri- 

 stome each ambulacrum, as said above, has a pair of them 

 larger than the rest and joining together from either side just 

 under the spherid, on the middle of the external margin, Jig. 

 4, 7. Under the microscope they are all of them glossy and 

 covered with regularly disposed extremely delicate punctures, 

 fg. 7, 9, 10. They are epistromal protuberances, such as are 

 scen under some form or other, in perhaps all Echinoids, as 

 I have attempted to show *). 



The calycinal system is löst, fig. 2, ^, and with it the 

 adjoining parts of the ambulacra I, III, IV and V, and the 

 interradia 1, 2, 3, 4. The ambulacrum II alone terminates 

 dorsally with a minute incision that seems to mark the site 

 of the löst radial II of the calyx. Of the III a small part 

 is löst, and more of the IV. Of the bivium, I and V, a con- 

 siderable portion is destroyed. If the lines of its poriferous 

 zones are drawn out to their endings, these seem to have fallen 

 in with the corresponding radials at some little distance from 



') On the Echinoidea described by LlNN^US, Bihang till Sv. Vet. 

 Akad. Handlingar, XIII. 



