REPOET ON THE ECHINOIDEA. 115 



Station 46. May 6, 1873. Lat. 40° 17' N., long. 66° 48' W. ; 1350 fathoms; 

 bottom temperatui'e, 2*3° C. ; mud. 



Echinus angulosus. 



Cidaris angulosa, Leske, 1778, Kl. Add. 



Ecldims angulosiis, A. Agassiz, 1872, Eevis. EcL, part 1, p 122. 



Simon's Bay; 10 to 20 fathoms. 



Echinus elegans. 



Echinus elegans (Dub. o. Kor.), 1844, Skand. Ech. 



Station 46. May 6, 1873. Lat. 40° 17' N., long. 66° 48' W., 1350 fathoms; 

 bottom temperature, 2'3° C. ; mud. 



Tristan da Cunha; 1100 fathoms. 



Station 219. March 10, 1875. Lat. 1° 50' S., long. 146° 42' E. ; 150 fathoms 

 mud. 



* Echinus horridus (PI. VL" figs. 1-5). 



Echimis horridus, A. Agassiz, 1879, Proc. Am. Acad., vol. xiv. p. 203. 



Fragments of a large conical Echinus were collected in the Straits of Magellan, 

 which I am unable to refer to any of the species already known from that locality. It 

 is readily characterised by its narrow poriferous zone, with its three pairs of pores, distant 

 and placed in nearly vertical arcs on the abactinal surface (PI. VL" figs. 3-5), but so 

 spaced that the two outer pairs form one vertical line, and the inner a second one ; on 

 the actinal side the poriferous zone is wider, the arcs are more horizontal, and placed 

 nearer together (PI. VL" fig. 4). Both in the ambulacral and interambulacral areas, the 

 single primary tubercle placed on each coronal plate (PL VL" figs. 3, 4, 5) forms a most 

 distinct vertical row. On the actinal side the primaries of both areas are nearly of a size 

 (PI. VL" fig. 4), but on the sides of the test, above the ambitus, the ambulacral primaries 

 decrease in size more rapidly than the corresponding interambulacral ones, as they 

 approach the abactinal system (PI. VL" figs. 3, 5). On the actinal side the secondaries 

 are irregularly arranged, and the intertubercular space of the plates is closely packed 

 with miliaries and small secondaries, showing no definite arrangement (PI. VL" fig. 4). 



On the sides of the test, however, some of the larger miliaries and secondaries form 

 diverging lines more or less parallel to the horizontal sutures of the plates (PI. VL" figs. 

 3-5). This linear arrangement of the secondaries and miliaries is most prominent near 

 the ambitus (PI. VL" fig. 3). The primary spines (PI. VL" fig. 2) are remarkable for 

 their length, being even comparatively longer than in some specimens of Echinus acutus. 

 The actinostome is comparatively smaller than in any other species of this genus, not as 

 large as the abactinal system, with but slight buccal indentations. The actinal system was 



