KONGL. SV. VET. AKAD. HANDL. BAND 19. N:0 7. 53 



there lies a ring of strong, transversal, arcuated and branched spicules, and that the 

 central part is sustained by about five, finely areolar, converging, and convex laminaei. 



Among the genera provided with a peripetalous or an internal fasciola, such 

 continuance of simple pedicels all through the length of the frontal ambulacrum has 

 been observed only in Meoma and Lovenia. In Meoma ventricosa and M. grandis, 

 both of which huge species have a Avell-marked, tliough narrow peripetalous fasciola, 

 the frontal pedicels, Pl. VIII, fig. 70, surprisingiy minute, present the same uniform 

 simple structure all along, from the phyllode to the calyx, just as those of I a and 

 V h do within the subanal fasciola. The central eonvexity is lobate, much as in the 

 subanals of Schizaster, and the spicular structure is that just described in Spatangus. 

 Very minute are also the simple frontal pedicels within the internal dorsal fasciola of 

 Lovenia, PL X, jig. 107, 108, and similar in structure to those of Spatangus. 



Among the Prymnadetes, Hemiaster expergitus n., Pl. X, jig. 92, ^) the most an- 

 cient generic type among recent Spatangida3, presents, within the peripetalous fasciola, 

 middle-sized pedicels, terminating in a flat disk, slightly waved at the margin, strength- 

 ened by ten or eleven elongated, reticular, calcareous lamels, which in their outer, 

 larger and horizontal portion are of a more open texture and lacerated at the margins, 

 in the inner, tapering and feebly rising portion, more compact, smooth-margined and 

 contiguous, leaving a clear space in the centre. Slightly different from this is the 

 terminal disk in Abatus Philippii, jig. 91, not much exceeding the tubular shaft, cir- 

 cular and sustained by areolar lamels up to twelve in number, sub-triangular, rather 

 flat throughout, more dense and less rough-margined in their inner tapering portion. 

 But it is in the singular Palaäostoma mirabile and in the group formed by Schizaster, 

 Moira and Aceste, that this structure of the terminal disk is more highly developed, 

 the pedicels at the same time attaining unusual dimensions, so as to make their rows 

 form a very striking feature of the frontal ambulacrum. In all of them the disk is 

 wide, and strengthened by numerous radiating lamina3. In Palasostoma, Pl. XVI, jig. 

 194, it is octo-stellate, and the laminte, outwardly lanceolate, have their inner portions 

 broad and spade-like. In Schizaster fragilis, D. & K., Pl. X, jig. 100, its margin is 

 digitate, deeply divided into from fifteen to twenty three rays, expanded at the top, 

 each of them for about half or tAvo thirds of its length supported inwardly by a long, 

 nearly linear lamel, lacerated at its growing end, otherwise nearly smooth-margined, 

 with its inner portion slightly rising, and tapering to an obtuse point. The same re- 

 appeai's in Schizaster japonicus Al. Ag., jig. 101, 102, 103, in which the margin is less 

 deeply digitate, and the lamella3, even exceeding thirty in number, are very long and 

 nai"row, and have their inner ends slightly dilatated. In Moira atropos, jig. 94, 95, 

 on the other hand, the inner contiguous portions of the lamellte are broad, spade-like 

 and smooth-margined, thus contrasting with the outer portion which is narrow, linear 

 and jagged. In Aceste bellidifera Wyv. Thoms., ftg. 96, 97, 98, which has received its 

 name from the size and singular appearance of these pedicels, the broad expanse of 

 the disk is only slightly waved in front of each of the twenty to twenty seven rod- 



') Études, p. 13, pl. XII, iig. 114—120; XI, tig. 93, 94; V, lig. 46, 47, 



