GENEEA AJ^B GEOUPS 01" THE ECHINOIDEA. 279 



into one ; two large genital pores upon conical protuberances. 

 Madreporite indistinct. Eadial plates small, separate. 



Ambulacra dissimilar, sunken, the anterior in a sligbt abac- 

 tinal groove, the plates rather high ; the pairs of small pores 

 vertical and in two rows. Petaloid part of the antero-lateral 

 ambulacra divergent, broad, poriferous zones broad ; postero- 

 lateral petals shorter. The plates beyond the petals broad with 

 single pores, but narrowing greatly at the peristome ; the postero- 

 lateral areas wide on either side of the sternum, the fifth plate of 

 the inner zone of the right posterior ambulacrum actinally 

 pushing into the line of the posterior interradium. Phyllodian 

 tentacles with a central protuberance and marginal filaments. 

 Erontal tentacles with a calcareous disk and rays. Primary 

 tubercles perforated and crenulate, numerous on the large inter- 

 radial plates. 



Interradia with few plates ; both the antero-lateral areas with 

 the second plates of both their zones beyond the peristomial 

 plate united, the same union occurs in the left postero-lateral 

 interradium. In the right postero-lateral interradium there is 

 union of the second plates of both zones with the third plate of 

 zone " &." The peristomial plate of the odd interradium is long ; 

 the sternum is not quite symmetrical, the second plate of zone 

 " h " being short ; the episternal plates are not parallel. 



Peristome excentric in front, nearly flush, pentagonal, the 

 greater part of the margins formed by interradial plates, the am- 

 bulacra forming the angles and very small ; five triangular buccal 

 plates. Periproct circular, near the upper extremity of the 

 rounded posterior surface, 5-7 triangular plates on its membrane. 

 A sinuous peripetalous fasciole. Spines and tubercles subequal, 

 the former subulate and largest dorsally. 



Recent. China, East Indian Islands. 



IV. Pamily Pouetalesiid^, 



(Pourtalesiadse) Loven, 1883, Kongl. Svensk. Vet.-ATcad. Sandl. 

 Bd. xix. no. 7, p. 82 (Pourtalesia). 



Syn. Subfamily Pourtalesice, Wyv. Thorns. & A. Agass. (pars). 



Test very elongate, subcylindrical or obconical, truncated 

 anteriorly and broad there, tumid in the middle and rostrated or 

 pointed posteriorly ; convex or humped dorsally, flat actinally. 



