METALIA PECTORALIS. 361 



Metalia pectoralis 



Echinus grandis Gmel. 1788. Linn. Syst. Nat. 



1 Metalia pectoralis A. Agass. 1872. Rev. Ech., Pt. I. 



PL XXI. f. 4, 5. 



The specimens of this species usually preserved in museums are almost 

 invariahly denuded tests, and we have therefore a very imperfect idea of the 

 natural features of this fine Spatangoid. The few spines still remaining on 

 one of the specimens I have seen, corresponding to the small tubercles covering 

 the test, are quite short, greatly curved ; those of the large tubercles within 

 the peripetalous fasciole I have not seen. On a small specimen, part of the 

 spines of the actinal side are still left ; they resemble the spines of Lovenia, 

 are long, slender, strongly curved eccentrically near the broad base, so that 

 we may assume that the spines of the large dorsal tubercles were probably 

 of the same structure. The test is thin, more or less elliptical, though with 

 increasing size the edge becomes somewhat angular, the median interambu- 

 lacral spaces re-entering slightly. The outline in profile is regularly arched 

 in small specimens, but in older ones we frequently find a gradual sloping of 

 the test from the edge to the apex, others retaining the more regularly arched 

 outline. The vertex is anterior, corresponding to the abactinal system. The 

 odd anterior ambulacrum is placed in a slight groove. The anterior pair of 

 ambulacra are shorter than the posterior, — the anterior slightly curving an- 

 teriorly, the posterior diverging, on the contrary, at the extremity. The peri- 

 petalous fasciole is broad, sometimes sunken, somewhat elliptical, except the 

 anterior angle made previous to crossing the odd ambulacrum. A slight ridge 

 extending to the apex divides the anterior interambulacrum into a portion 

 bearing large tubercles next to the anterior pair of ambulacra, and into the 

 part adjacent to the odd ambulacrum, where the primary tubercles are numer- 

 ous but small. The whole space of the lateral interambulacrum above the 

 peripetalous fasciole is crowded with large primary tubercles with a broad 

 scrobicular circle, except the part immediately adjoining the posterior edge 

 of the anterior ambulacra, which is divided by a slight ridge from the re- 

 maining part of the interambulacral space. The same is the case with the 

 narrow posterior interambulacral space ; a ridge separates the space free of 

 tubercles adjoining the posterior edge of the posterior ambulacrum from that 

 covered by tubercles ; the tubercles of the odd posterior interambulacrum are 

 smaller than those of the lateral posterior ambulacra, where the primary tuber- 

 cles take the greatest development. The difference between the length of 



