ECHINOTHURID.E. 75 



plates of the genital ring, Fig. 112 7 . In D. horridum Figs. 96, 100, and in 

 D. globulosum, Fig. 125, the youngest interambulacral plates push their way 

 between the oculars and genitals. 



The characters of the genital ring of the Aspidodiadeinatidae are emi- 

 nently archaic. It is only in the Melon it id 33 and Bothriocidaridae and in 

 some of the older Cidaridae that we find the genitals and oculars all in 

 contact with the anal system. 



Station 3362 between Cocos Isd. and the mainland, 1175 fathoms. Lat. 

 5 56' N. ; Long. 85' 10' 30" W. Bott. temp. 36°.8. Gn. m. s. Rocky. 



Station 3363 between Cocos Isd. and the mainland, 978 fathoms. Lat. 

 5° 43' N. ; Long. 85° 50' W. Bott, temp. 37 .5. Wh. glob. ooze. 



Station 3364 between Cocos Isd. and the mainland, 902 fathoms. Lat. 

 5 30' N. ; Long. 86° 8' 30" W. Bott. temp. 38°. Yel. glob. ooze. 



Station 3375 south of Malpelo Isd., 1201 fathoms. Lat. 2 34' N. ; Long. 

 82° 29' W. Bott. temp. 36°.6. Gy. glob. ooze. 



Station 3376 near Malpelo Isd., 1132 fathoms. Lat. 3° 9' N. ; Long. 82° 

 8' W. Bott. temp. 36 .3. Gy. glob. ooze. 



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

 80° 52' 30" W. Bott. temp. 35.8. Gn. M. 



Station 3398 off Galera Point, 1573 fathoms. Lat. 1° 7' N. ; Long. 80° 

 21' W. Bott. temp. 36°. Gn. ooze. 



Station 3400 from Galera Point to the Galapagos, 1322 fathoms. Lat. 

 ? 36' S. ; Long. 86 3 46' W. Bott. temp. 36°. Lt. gy. glob. ooze. 



Station 3413 northwest of Culpepper Isd., Galapagos, 1360 fathoms 

 Lat. 2° 34' N. ; Long. 92 : ' 6' W. Bott. temp. 36°. Glob, ooze, drk. sp. 



Bathymetrical range, 902 fathoms to 1772 fathoms. Extremes of 

 tempei'ature, 38°-35°.8 



ECHINOTHURID-SI Wyv. Thorn. 



We may be justified in assuming that the anal system is in the Echino- 

 thuridse, as in the Cidaridae, covered by five small anal plates; but in none 

 of the young specimens I have had occasion to examine was it possible to 

 determine their primitive grouping, though in a young specimen of Ph. 

 placenta of 7 mm. (PI. 43, fig. 2) there seem to be five plates in the angles 

 of the anal pentagon somewhat larger than the others. Their development 

 is evidently quite irregular, as is seen in a somewhat older stage of the 



