168 GONIOPHORUS 



ovarials have a rliomboidal figure, the postero-laterals an irregular shape, occasioned 

 by the lateral extension of the vent, and the single plate is still longer and narrower by 

 reason of the space occupied by the same aperture ; the oviductal holes occupy the centres 

 of the sides of the pentagon near the point touched by the diagonal carinse that cross the 

 ovarial plates. The ocular plates form small triangular bodies, the apices of which touch 

 the summits of the ambulacra (fig. 2 b) ; in neither of the fine specimens from Mr. 

 Cunningham's collection, nor in those from the School of Mines, which were selected as the 

 best extant for figuring, could the sutures of the ovarial and ocular plates be seen. I have 

 only discovered them now, April, 1871, long after the drawings were executed.in an otherwise 

 indifferent specimen of my own, collected many years ago, and I have been able therefrom 

 to trace out these sutural lines satisfactorily, and complete my description of the apical 

 disc of this most curious and beautiful Salenia. The vent is transversely oblong, inclining 

 to an angular figure, and surrounded by a ridge of the test, which well defines its 

 boundary, and forms a prominent periprocte at the same time. The carinse of the disc 

 cross the sutures of the plates in all directions, especially those anterior to the periprocte, 

 and convert its surface into a series of seven triangles when all the ridges are preserved 

 entire. 



Affinities and Differences. — This Urchin is so entirely different from other Salenid^ 

 in the structure of its apical disc that it forms a type quite distinct from all the others ; 

 the calcareous processes or carinse on the surface of the ovarial and ocular i)lates have 

 nothing whatever to do with the sutural fines which unite the elements of the discal 

 apparatus, whereas in Peltastes and Salenia the figures on the disc are always developed 

 in the line of the sutures. 



Locality and Stratigrapldcal Position. — This Urchin has been collected from the 

 Upper Greensand near Warminster; on the Continent it is a very rare fossil. The 

 original specimen was found in the Etage Cenomanien, at Cap la Heve, near Havre, Seine 

 Inferieure ; others from the same stratum at Vaches Noires, Calvados, and Vimoutiers, 

 Orne ; in all these localities it is reported as being very rare. 



History.— Yix%i described and figured by Professor Agassiz in his ' Monographic sur 

 les Salenies.' In this work he described two forms as distinct species, G. lunulatus 

 and G. apicidatiis, which I consider as varieties only of the same Urchin. Professor 

 Agassiz afterwards gave the MS. name G. favosus to a form of this group which 

 he saw in the collection of Mr. Bunbury, of London, and the name found its way into 

 Professor Morris's ' Catalogue of British Fossils,' 1 st Edition ; this variety exhibits only 

 a slight deviation from the type form, so that the singular genus GoniojAorus is at 

 present represented by the beautiful little Urchin now under consideration. Seeino- 

 that so many examples of Salenid.e have been collected from the Upper Greensand of 

 England, and the Cenoraanian stage of France, during the last forty years, it is remarkable 

 that no true second species has been found. It has often occurred to me that this is 

 one of many problems of a like nature that the disciples of Darwin might attempt to 



