116 THE VOYAGE OF H.M.S. CHALLENGER. 



entire only in a medium-sized specimen, but the fragments of the actinostome of a large 

 specimen show that it does not increase greatly with age. The colour of the test (when 

 dry) is light reddish-brown, the miliary and secondary spines of a darker colour, the 

 shaft of the primary spines of the same colour as the test, somewhat darker at the base. 



The aliactiual system is remarkal)ly compact and solid, with five large heptagonal 

 plates covered by a close granulation of small secondaries (PI. VI." fig. 1), with large 

 genital openings placed close to the outer edge of four of the plates. The madreporic 

 plate is somewhat larger than the others, the madreporic body covering nearly the whole 

 plate with the exception of the anal edge of the plate, which is covered by small 

 secondaries like the other plates. The ocular plates are of uniform size, irregularly 

 pentagonal, extending but little beyond the edge of the genital plates ; they are covered 

 with smaller secondaries than the genitals ; the ocular pore is large. The anal system is 

 covered by an outer row of large plates, one of which from its size is probably the 

 original anal plate of the young, the rest of the anal system is covered by small 

 irregularly-arranged plates (PI. VI." fig. 1). 



There are two kinds of pedicellariee, one small-headed, long-stemmed; the other short- 

 stemmed with a conical head ; the latter are the more numerous on the test. 



This species is closely allied to Echinus norvegicus, judging at least from the medium- 

 sized specimen, measuring 47 mm. in diameter (actinostome 8 mm.). This species, 

 however, from the size of the fragments of the sides of the test, must attain a height of 

 nearly 100 mm. 



It has, like Echinus microstoma of Thomson (Porcupine Echinoidea, Trans. Eoy. Soc, 

 vol. clxiv. part 2, pi. Ixviii. fig. 1), a small, somewhat sunken actinostome, but difiers from 

 it in the arrangement of the secondaries and miliaries. 



Station 308. January 5, 1876. Lat. 50° 10' S., long. 74° 42' W. ; 175 fathoms; mud. 



Echinus magellanicus. 



Echinus magellanicus, Phil., 1857, Wieg. Arch., vol. i. 



Station 315. January 26, 1876. Lat. 51° 40' S., long. 57° 50' W.; 5 to 12 fathoms ; 

 sand and gravel. 



Station 304. December 31, 1875. Lat. 46° 53' S., long. 75° 11' W. ; 45 fathoms ; sand. 



Station 308. January 5, 1876. Lat. 50° 10' S., long. 74° 42' W. ; 175 fathoms ; mud. 



Marion Islands ; 50 fathoms. 



Station 145. December 27, 1873. Lat. 46° 40' S., long. 37° 50' E.; 310 to 315 

 fathoms. Prince Edward Island. 



Station 147. December 30, 1873. Lat. 46° 16' S., long. 48° 27' E. ; 1600 fathoms; 

 bottom temperature, 0'8° C. ; globigerina ooze. 



Station 312. January 13, 1876. Lat. 53° 38' S., long. 70° 56' W. ; 10 to 15 fathoms; 

 mud. 



