AEROPE FULVA. 197 



what stouter than those within the peripetalous fasciole ; at the ambitus 

 they are not only longer but more uniformly spathiform, as also on the 

 actinal and anal plastrons. 



The longitudinally elliptical actinal system (PI. 62, fig. 4) is almost bare ; 

 it is covered with but few and insignificant elongated plates. The anal 

 system is elongate, angular in outline. The anal opening is subcentral 

 nearer the posterior edge; it is covered by small concentrically arranged 

 irregularly shaped plates, the anterior of which carry a few miliaries with 

 an inner row of elongated plates radiating from the actinostoine. 



On coming up in the trawl the specimens are of a dark yellowish 

 brown color. 



In the "Challenger" Report, 1 Aerope was placed among the Brissina, 

 and the same position was assigned to it in the Preliminary Report on 

 the Echini of this expedition.- This is evidently not quite correct. A 

 closer analysis shows Aerope to be allied to the Ananchytidae as well as 

 to the Brissina; it is more closely related to Homolampas than to the 

 Brissina proper. In spite of its prominent peripetalous fasciole, so similar 

 to that of the young of Hemiaster and of Brissopsis and its rudimentary 

 petaloid system, it has the actinal system of the Ananchytidae, a peripetalous 

 fasciole as in Homolampas, and the double-pored primitive ambulacra! 

 petals of Phrissocystis and Paheohrissus, but enclosed in a peripetalous fas- 

 ciole ; this is specially well developed in the odd anterior ambulacrum of 

 Aerope (PI. Gl, fig. 4). Aerope has also the cydindrical outline which 

 characterizes Pourtalesia and the .young Brissinae ; on the whole, while 

 retaining Aerope among the Brissina, we should not neglect to recognize its 

 Ananchytid affinities. 



Station 3361, on the w 7 ay to Cocos Island from Mariato Point, in 1471 

 fathoms. Lat. 6 10' N. ; Long. 83 6' W. Bottom temperature 36.6. 

 Gn. ooze. 



Station 3362, on the way to Cocos Island from Mariato Point, in 1175 

 fathoms. Lat, 5 56' N. ; Long. 85 10' 30" W. Bottom temperature 

 36 .8. Gn. m. S. rocky. 



Station 3381, north of Malpelo Island, in 1772 fathoms. Lat. 4° 56' N. ; 

 Long. SO' 52' 30" W. Bottom temperature, 35°.8. Gn. m. 



Station 3398, off Galera Point, in 1573 fathoms. Lat. 1° 7' N. ; Long. 

 80° 21' W. Bottom temperature 36'. Gn. ooze. 



" " Challenger " Echinoidea, p. 190. "- Bull. M. C. Z XXXII. No. 5, p. 81. 



