72 



ECHINOIDEA. I. 



given by Wyv. Thomson, the statement is not to be relied on, as the most characteristic feature of 

 these, the irregular edge of the terminal part of the blade, has not before been observed. 



The statements in the literature with regard to the distribution of this species, are upon the 

 whole quite unreliable, as we cannot be sure that it is really this species which has been examined 

 in each case. No doubt the statements apply often to Arceosoma fenestratum, and probably also to 

 A. elh"Mrtsn. (see above p. 54 55), which has likewise been confounded with C. hystrix. It ma}', however, 

 be taken to be probable that its distribution is the same as that of Phormosoma placenta, viz. ca. 100 

 ca. 1000 fathoms along the coasts of Europe and North America, and across the Atlantic south of 

 Iceland. It is only known from the territory with positive bottom temperature. In the <.cold area 

 it is certainly not found. 



7. Araeosoma fenestratum (Wyv. Thomson). 



PI. XI. Fig. 8. PL XII. Fig. 33. PI. XIV. Figs, i, 8, 14, 17, 18, 24, 32. 

 Synonyms : Calvcria fenestrata Wyv. Thomson. 

 Asthenosoma fenestratum (A. Agass.). 



Reynoldsii A. Agass. 

 Non: Calveria (Asthenosoma) hystrix Wyv. Thomson. 



Principal literature: Wyv. Thomson: Echinoidea of Porcupine* (395) p. 741. PL LXIII. 9 10, 

 LXVILXVIL A. Agassiz: 6. p. 75. Blake-Echini (9) p. 29. PL XIII XIV. (^Asthenosoma hystrix*). 

 W. E. Hoyle: Rev. List of Brit. Echinoidea (202). p. 408. -- F. Jeffr. Bell: 72. PI. XXIV. Fig. i, 

 PL XXV. 



The reasons why this species is not, as has been supposed by Bell (72) and Koehler (229), 

 synonymous with Calvcria hystrix, but on the contrary must be referred to another genus, have been 

 given above (p. 52 53). In Preliminary Report of the Blake -Echini* (6. p. 75) Agassiz describes an 

 Asthenosoma by the name of A. Reynoldsii, readily distinguished from A. hystrix by the larger, higher 

 coronal plates, the prominent vertical row of primary tubercles on the outer edge of the interambu- 

 lacral area on the abactinal side, the less numerous secondaries and miliaries and the color of the test. 

 The primary spines, quite closely packed, on the actinal side, are long, slender, slightly curved, and 

 trumpet shaped; on the abactinal side they form one principal vertical row extending half-way to the 

 apical system near the outer edge of the interambulacral areas. The rest of the test is covered by 

 distant small secondary spines. After having examined a great many specimens, Agassiz has later 

 (9. p. 29) got the conviction that the specimens he separated as A. Reynoldsii, are only large speci- 

 mens of Asthenosoma hystrix; the differences, striking as they appear, are merely due to age. 



From the Ingolf (st. 89) we have a specimen, no doubt identical with the <tA. Rcynoldsin of 

 Agassiz; it agrees very well with the description quoted, and with a specimen received from U. S. 

 National Museum under the name of Asthenosoma hystrixv, and both agree exactly with a fragment 

 of a type specimen of Calvcria fenestrata which I had occasion to examine in British Museum (see 

 above p. 53). It is true that the tetradactylous pedicellariae are wanting in both specimens as well as 

 in the mentioned type specimen; but in all other respects they are quite similar, and above all, the 

 tridentate pedicellarise are identical in all of them. There can be no doubt that the long missed, at 



