ABATUS CAVERNOSUS. 211 



and the narrow ambulacral areas of the actinal side (PI. XXXV '', fig. 2) 

 as contrasted to tlie broad ambulacral areas of 7*. lirnicula from the Gulf 

 of Mexico (PI. III. fig. 4).' 



The Mexican species is far more closely allied to the Panamic specie.s 

 than to the Schizaster-like specimens collected by the " Challenger." The 

 abactinal system of the latter resembles that of Schizaster, while that of 

 P. limicola and P. tenuis are Hemiaster-like, though that of P. limicola has 

 only two genital pores. 



Station 3381, off Galera Point, 1772 fathoms. Lat. 4' 56' N. ; Long. 

 80^ 52' 30" W. Bottom temperature, 35°.8. Gn. m. 



Station 3398, off Galera Point, 1573 fathoms. Lat. 1' 7' N. j Long. 

 80" 21' W. Bottom temperature, 36 \ Gn. ooze. 



Station 3399, off Galera Point, 1740 fathoms. Lat. 1' T N. ; Long. 

 81° 4' W. Bottom temperature, 36°. Gn. ooze. 



Bathymetrical range, 1573-1772 fathoms. Temperature range, 36 -35\8. 



Abatus Trosch. 

 Abatus cavernosus Tiosch. 



Tripylus cavernosus, Phil. Wieg. Arch. 1845, XI, p. 345. 

 Abatus cavernosus, Trosch. Wieg. Arch. 1851, XVII, p. 72. 



Plate 99. 



The Echinid-like type of young Spatangoids has been known since 

 1848 from Muller's figures. Subsequently I figured a number of post- 

 embryonic stages of young Spatangoids in the Revision of the Echini 

 (1874), the "Challenger," and "Blake" Echini. In 1883 Loven carefully 

 described and figured the young of Abatus cavernosus and of Echinocar- 

 dium,^ while we owe to Fewkes and Theel more recent figures of very early 

 Echinid stages of Echinarachnius and Echiuocyamus. In Loven's figures 

 of a young Echinocardium ^ of 1.7 mm. in length the coronal plates of 

 the young Spatangoid are drawn and the fascioles are indicated. In his 

 figures of a young Abatus of 2.3 mm. the plates near the actinostome are 

 figured,'' as well as those of the abactinal system and part of those of the 

 ambulacral system. The interambulacral plates are not shown. 



J Bull. M. C. Z. 1878, No. 9, Vol. V, p. 193, PI. III. 

 2 Pourtalesia, p. 24, Pis. XIV, XV. 

 « Pourtalesia, PI. XV, figs. 172, 173 

 * Pourtalesia, PI. XIV, figs. 166, 167. 



