4^34 Miscellaneous. 



trace of its insertion, whilst on all the inferior plates, when the spine 

 has been lost, the place to which it was attached is distinctly re^- 

 cognizable. The marginal plates all fit accurately together without 

 intervening granules. The dorsal surface is covered with smaller, 

 polygonal, convex plates, also densely granulated ; the granules re- 

 semble those of the marginal plates, and are smaller and less elevated 

 than those of the ventral surface. The back of each arm forms a 

 blunt radial elevation (but not a sharp keel), along which there is a 

 simple series of spines, formed like those of the marginal plates, but 

 larger. Near the middle, the five elevations unite to form an annular 

 wall, which encloses a somewhat depressed central surface. A few 

 larger spines stand on this central surface, but without being defi- 

 nitely arranged in any of the five radial rows. Lastly, one larger 

 spine stands in the middle line of each interradial space, near the 

 margin. No pedicellarise are to be found on the single specimen. 



Radius of the disk 48, of the arms 69 millim. Height of the dry 

 specimen, without the spines, 18 millim. 



Islas los Negritos, in the Gulf of Nicoya, Costa Rica ; collected 

 by M. Hoffmann in 1857, and afterwards sent to the Berlin Museum. 

 Colour, when alive, tile-red, according to Hoffmann's notes. 



In the * Annals and Magazine of Natural History,' vol. vi. p. 277 

 (1840), Dr. Gray briefly described a new species under the name of 

 Pentaceres armatus ; he gives as its habitat Punta Santa Elena. He 

 founds upon it a peculiar subgenus, Nidorellia, which he characterizes 

 as follows : — " Back regularly convex, formed of flat granular ossi- 

 cula, with a blunt mobile spine on the centre of each ossiculum 

 below ; arms short and broad." 



Miiller and Troschel were not acquainted with this species, and 

 under the name of Oreaster armatus they merely give a German 

 translation of Gray's words, in which, however, they omit the word 

 ** below," evidently because they could not understand Gray's ex- 

 tremely obscure mode of expression without comparison with a speci- 

 men. Hence must have originated the misconception which repre- 

 sents it as if each plate on the dorsal surface bore a spine, which, 

 however, is not the case, as I have ascertained from the original 

 specimen in the British Museum. Dujardin and Hupe' (Hist. Nat. 

 ^es Zoophytes Echinodermes, p. 387) retranslate the above transla- 

 tion into French, without adding anything new, except an error and 

 a fresh cause of error, In the first place, of the words *' the inferior 

 marginal plates and the three last superior ones, &c., with spines," 

 they have overlooked the httle word *' superior," and translated them 

 "les plaques margina,les inferieures et plus particulierement les trois 

 d^rnieres." In the second place, they give as the habitat simply 

 ** Sainte-Helene," from which every one would at once be led to 

 think of the well-known island in the South Atlantic Ocean, and not 

 of the Cape on the west coast of Ecuador, not far from Guayaquil. 

 Under these circumstances I considered it by no means unnecessary 

 to give a detailed description of the species after the fashion of those 

 drawn up for other species by Miiller and Troschel, even without the 

 particular circumstance which I have now to mention, and to which 



