7 6 



ECHINOIDEA. II. 



ends down on the sides, not reaching the edge. There is a somewhat larger, though very inconspicuous 

 tooth at the point In larger specimens (PI. XL Fig. 24) the valves become more slender and elongated 

 and the tooth at the point more prominent, and in the largest ones (ca. o-2 mm head) the tooth at the 

 point is very long, the blade narrow, the edges serrate only in the outer part, where the valves join. 

 (PL XI. Fig. 5.) -- The rostrate pedicellarise (PL XI. Figs. 17, 27, 28) differ considerably from those of 

 P.Jcffreysi and Wandcli. The blade has not the outer edge sharply set off from the sides; the point 

 is simply rounded, set with some slender teeth, which continue some way down the side-edges; the 

 edges are rather thick, having only a small deepening along the middle of the blade with few holes 

 there, and sometimes near the point a transverse beam, which may be provided with a tooth. These 

 pedicellarise may be invested in a rather thick, pigmented skin. The ophicephalous pedicellariee 

 (PL XI. Figs. 3, 6, 32) are not so beautifully developed as in Jcffreysi and Wandcli, though agreeing 

 in the main points with these. The outer end of the valves is hardly widened and with rather few 

 teeth along the edge. I have found only two specimens of them, at the anal area. Also the rostrate 

 pedicellarise occur mainly near the anal area; the larger tridentate pedicellarise I have found within 

 the oral invagination. 



Regarding the inner anatomy I cannot give full information, as I do not want to destroy 

 one of the better preserved specimens. In a crushed specimen the intestine is preserved; the walls 

 are, however, so incrusted with the Globigerina-mud, which fills the intestine, that it is impossible to 

 discern the convolutions with certainty; likewise I am unable to ascertain the presence of a diverti- 

 culum or of the siphones, though it can scarcely be doubtful that they will be present as in other 

 Pourtalesiae. -- As in P. Jeffreysi and Wandcli the genital organs differ considerably in shape in the 

 two sexes: large, bush-shaped in the males, simple tubes in the female. The male genital organs are 

 situated one behind the other, far back, the posterior one at the beginning of the body, and connect 

 with the genital openings through very long efferent ducts, passing up the whole length of the neck. 

 (PL VII. Fig. 16.) In the female the genital organs are situated in the ihead, having rather short oviducts. 

 (PL VII. Fig. 10). The stone-canal evidently runs as in P. Jeffreysi, making a great curve backwards, 

 following the intestine into the body; to be sure I have been unable to trace it in its whole length, 

 only the two ends of it (PL VII. Fig. 16), but the fact that it passes backwards through the whole 

 length of the neck along the dorsal side does not leave any doubt that its course must upon the 

 whole be as in P. Jcffreysi. There is a slight thickening, representing the axial organ, near the upper 

 end of the canal. Below the ankylosed genital-madreporic plate there is a rather large calcareous pro- 

 cess, to which the end of the stone-canal is fastened. The radial water-canals of the bivium are very 

 thin and inconspicuous, those of the trivium are more distinct; ampullae I have been unable to find. 



This species was taken by the Ingolf* at the following stations: 



St. 40 (62 oo' Lat. N. 21 36' Long. W. 895 fathoms 33 C. Bottom temp.) i specimen. 



- 68 (62 06' 22 30' 843 34 1(2?) (fragments) 



- 83 (62 25' 28 30' 912 35 4 (two in fragments). 



The species is thus known only from off Southwest Iceland, from a depth of 843 912 fathoms. 

 That it will prove to be distributed over a large part of the warm area of the northern Atlantic can 

 scarcely be doubted. 



