40*2 Annals of the South African Museum. 



* METALIA SPATAGUS. 



Echinus spaiaijus Linne, 1758. Syst. Nat. ed. 10, p. 665. 



MetH<t sjxitni/ufi Loven, 1887. Ech. Linn., p. 16 



Met<tli<i nxiniloxii A. Agassiz, 1873. Rev. Ech., pt. 3, pi. XX I/;, ligs. 8, 9. 



This species is included here with great trepidation and solely on 

 the strength of the reports that Peters took it at Mozambique in 1854. 

 It is known from Mauritius but not from Zanzibar. 



SPATAGOBRISSUS * MIRABILIS gen. et sp. nov. 

 Plate XXIII. 



Test wide, low, well rounded in front, the ambitus rounded behind, 

 but below ambitus interambulacrum 5 slopes abruptly forwards 

 making an oblique surface on which opens the longitudinally elongated 

 periproct. Peristome anterior, not deeply sunken. Ambulacrum III 

 narrow. Hush, not very distinct, ambulacra I and V moderately wide, 

 conspicuously petaloid, the petals rather long, bluntly pointed, dis- 

 tinctly depressed; ambulacra II and IV similar, the petals as long 

 or longer, and more divergent than I and V. Peripetalous fascicle 

 a single very distinct band, enclosing a nearly circular area, containing 

 numerous large primary tubercles. Subanal plastron small, subanal 

 fasciole very distinct. Genital pores 4. 



The above paragraph may serve for the generic diagnosis while 

 the following additional data apply more particularly to the species. 

 Test 112 mm. long, 95 mm. wide across anterior end of posterior 

 petals but only 90 across their tips, and 53 mm. high posteriorly 

 (about the same point as where widest) but only 43 high at peristome. 

 Anterior petals 36 mm. long and posterior pair about the same. 

 Anterior half of test above and below, inside and outside of peripe- 

 talous fasciole, crowded with primary tubercles, among which are 

 secondaries and numerous rniliaries also; the tuberculation is parti- 

 cularly thick in the midzone, outside the fasciole; on the posterior 

 half of the test there are no primaries outside the peripetalous fas- 

 ciole but within it they are nearly as numerous as anteriorly; even 



* The characters of this genus combine so strikingly those of Spatangus and 

 Brissus, it seemed to me fitting to combine those two generic names in one, 

 dropping the n of Spatangus for euphony's sake and to accord with the names 

 Spatagocystis and Spatagodesma. The significance of the specific name, mirabilis, 

 is obvious. 



