72 



ECHINOIDEA. I. 



given by Wj'v. Thomson, the statement is not to be relied on, as the most characteristic featnre 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 Arceosoiiia /fiicstratuiii, and probably also to 

 A. BeUi Mrtsn. (see above p. 54 — 55), which has likewise been confounded with C. hystrix. It may, 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. S. PI. XII. Fig. 33. PI, XIV. Figs, i, S, 14, 17, 18, 24, 32. 

 S>nonyms : Calvcria fenestrata Wyv. Thomson. 

 Asthcfiosoma fenestratn,))i (A. Agass.). 

 — Rcynoldsii A. Agass. 



Non: Cahcria (Asfhcnosoma) hystrix Wyv. Thomson. 



Principal literature: Wyv. Thomson: Echinoidea of Porcupine ^ (395) p. 741. PI. LXIII. 9 — 10, 

 IvXVI— LXVII. — A. Agassiz: 6. p. 75. Blake^-Echini (9) p. 29. V\.yA\\—^\\\{.Asthe)iosoma hystrix^). 

 — W. E. Hoyle: Rev. List of Brit. Echinoidea (202). p. 408. — F. Jeffr. Bell: 72. PI. XXIY. 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) A g a s s i z describes an 

 Asthenosoma by the name oi A. Rcynoldsii^ < readily distinguished ixo\\\ 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 clo.sely packed, on the actinal side, are long, slender, slightly curved, and 

 trumpet shaped; on tlie abactinal side they form one principal vertical row e.xtending 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. Rcynoldsii^ are only large speci- 

 mens of Asthenosoma liystrix\ «the differences, striking as they appear, are merelv due to age \ 



From the < Ingolf > (st. 89) we have a specimen, no doubt identical with the 'i.A. Reynoldsii>y of 

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

 National Miiseiun under the name of Asthciiosoii/a hystrixt^ and both agree exactly with a fragment 

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

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

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

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



