NATURAL SCIENCE8 OF PHILADELPHIA. 353 



sonne" of Agassiz. The collection made at the Bonin Islands was particularly 

 valuable in a historical point of view, as it enabled me to obtain precise 

 knowledge concerning the species of Echinoids which Mertens had collected 

 there, and which, though described by Brandt in his Prodromus, had never 

 been compared with the species described by Prof. Agassiz about the same 

 time. The annexed list is intended simply as a catalogue to give an idea of 

 the value of the collection, and the author hopes to return to this collection 

 on another occasion, and to give more lengthy descriptions, and figures of the 

 most interesting species. The notes of Dr. Stimpson, of the colors, and of the 

 depth at which the Echinoids were found, have been added in quotation 

 marks. These notes correspond to numbers attached to the specimens at the 

 time they were collected. 



PHYLLACANTHUS Brandt, Prod. 

 Syn. Leiocidaris Des., Syn. Echin. Foss. 



Phyllacanthus dubia Brandt, Prod. 



This species is, at first glance, so closely related to P. imperialis, that un- 

 questionably many of the errors which have been made in referring to P. im- 

 perialis this species, which is found in the Northern part of the Pacific Ocean, 

 arose from this close resemblance. The spines of P. dubia are more slender 

 than those of the imperialis. The longitudinal furrows are deep, equally well 

 marked along the whole length of the spine. It can at once be distinguished 

 from its congener by the narrowness of the median ambulacral zone, which 

 does not equal in width the poriferous zone ; the latter is somewhat de- 

 pressed. 



" Found among madrepores in one fathom, Port Lloyd, Bonin Islands. 

 Secondary spines of a deep purple ; primary spines ash color." (W. Stimp- 

 son.) 



Phyllacanthus fostigera Barn. MS. 



Small species, having one row of small tubercles round the scrobicular 

 circle of the ambulacral plates. Furrow joining the ambulacral pores very 

 deep. The spines are slightly plicated at the extremity ; the whole surface 

 minutely granulated. They are of a dark violet color, with two yellowish 

 rings placed about one-sixth of an inch apart, below the point where the pli- 

 cations commence. 



Taken at Puloe Leat Island, Gaspar Straits, Capt. Stevens. 



GARELIA Gray. Proc. Lond. Soc, 1855. 



Garelia cincta A. Ag., Bull. Mus. Comp. Zool., 1863. Syu. Echinothrix Tur- 



carum Pet?? 



" Spines of a purplish black color. Fine blue semicircular rays on the body, 

 among the bases of the spines, may be often noticed." 



" Hilo Hawaii. Found in rock crevices and under flat corals in the 4th 

 6ubregion of the littoral zone. Port Lloyd, Bonin Islands." (W. Stimpson.) 



DIADEMA (Peters emend.) Seeig. v. Mossamb. 



Diadema paucispinum A. Ag., Bull. Mus. Comp. Zool., 1863. 

 " Hilo Hawaii." (W. Stimpson.) 



Diadema nudum A. Ag. 



Under the name of Diadema turcarum no less than three different species 

 have been confounded. According to Peters, who had a specimen of what h-e 

 calls D. turcarum, it is an Echinothrix, entirely different from the D. setosttm 

 of Rumph., which he says is a true Diadema. Having examined in the col- 

 lection of the Museum at Cambridge, a remarkable sea urchin, received from 

 the Sandwich and Kingsmill Islands from Mr. Garrett, which agrees suffi- 



1863.] 



