ARBACIAD.E. 53 



Station 3357 off Mariato Point, 782 fathoms. Lat. 6^ 35' N. ; Long. 81' 

 44' W. Bott. temp. 38°.o. Modern greensand. 



Station 3360, on way to Cocos Isd., 1672 fathoms. Lat. 6' 17' N. ; 

 Long. 82° 5' W. Bott. temp. 36°.4. Fine blk. drk. gn. S. 



Station 3361 on way to Cocos Isd., 1471 fathoms. Lat. 6' 10' N. ; Long. 

 83° 6' W. Bott. temp. 36°.6. Gn. ooze. 



Station 3362 on way to Cocos Isd., 1175 fathoms. Lat. 5° 56' N. ; Long. 

 85° 10' 30" W. Bott. temp. 36°.8. Gn. M. S. Rocky. 



Station 3376 south of Malpelo Isd., 1132 fathoms. Lat. 3' 9' N. ; Ix)ng. 

 82° 8' W. Bott. temp. 36;3. Gy. glob. ooze. 



Station 3380, off Malpelo Isd., 899 fathoms. Lat. 4 3' N. ; Long. 81' 

 31' W. Bott. temp. 37°.2. Rocks. 



Station 3407, Galapagos Lsds., 885 fathoms. Lat. 0° 4' S. Long. 90° 24' 

 30" W. Bott. temp. 37°.2. Glob. ooze. 



Station 3411, Galapagos lsds., 1189 fathoms. Lat. 0° 54' N. ; Long. 91° 

 9' W. Bott. temp. 36^2. Yellow glob. ooze. 



Station 3413, Galapagos lsds., 1360 fathoms. Lat. 2° 34' N. ; Long. 92^ 

 6' W. Bott. temp. 36^ Glob, ooze dk. sp. 



Bathymetrical range, 782 fathoms to 1672 fathoms. Extremes of 

 temperature, 38°. 5 to 36°. 



ARBACIAD^ Gray. 



It has been impossible thus far to trace the development of the coronal 

 plates in the stages immediately following that of the free swimming Pluteus. 



Loven^ has figured a young Echinid of 0.6 mm. immediately after the 

 resorption of the Pluteus and its appendages, in which he show.s the ten 

 primitive buccal plates and traces of the five single actinal primordial inter- 

 ambulacral plates. He has also figured^ a much older specimen of a 

 Stro7igylocentrotus drohachiensis of 1.2 mm. showing the single interambulac- 

 ral primordial plates for the greater part intact, and in a still larger speci- 

 men of Echinus miliaris of 2.5 mm. Lov^n figures the single primordial 

 interambulacral plates as almost resorbed, only a fragment of each remain- 

 ing. ^ But these specimens and the young of Gopiocidaiis canaliculata 

 figured by Loven and myself give us no indication of the mode or order of 

 formation of the coronal plates of intermediate stages. 



1 fitudes, PI. XVTT, fig. 149. » Loven, Echinologica, PI. V, fig. 29. 



2 Loven, Echinologica, PI. IV, figs. 25, 26. 



