144 EC H IN IDEA. 



Distribution. Both sides of N. Atlantic from W. Indies to Rockall. 

 103-547 fms. 



a-k. 45 miles off Blackroek, 500 fms. Royal Dublin Society. 



/, m. 45 miles off Blackrock, 500 fins. Royal Irish Academy. 



n. A dried fragment, marked " type of Cal- ' Porcupine ' Exp. 



veria hysirix." 



o. Two dried fragments, marked u Sp. 1, ' Porcupine ' Exp. 

 fenestrated." 



2. PHORMOSOMA. 



Pkormosoma, Wyv. Thorns. Phil. Trans, clxiy. (1874) p. 732 ; Duncan, 

 J. L. S. xxiii. (1889) pp. 42 & 310; Bell, Ann. 8,- Mag. iv. (1889) 

 p. 437. 



An Echinothurid in which the coronal plates imbricate slightly, 

 and the ambulacral plates are narrow ; the areolae of the tubercles 

 that bear the primary spines are deeply sunken, and their impress 

 may be seen on the internal surface of the test. The calcareous 

 deposit in the coronal plates is greater than in Asthenosoma, and 

 there are no vertical muscular bands dividing the ccelom into 

 separate chambers. The organs of Stewart are not known to be 

 ever well developed. 



1. Phormosoma placenta. 



Pkormosoma placenta, Wyv. Thorns. Phil. Trans, clxiv. (1874) 



p. 732, pis. lxii. & lxiii. figs. 1-8 ; A. Ag. Bull. M. C. Z. x. 



(1883) p. 301, pis. xii. & xv. figs. 3-19 ; id. Proc. Bog. Soc. Ed. 



xi. (1883) p. 697 ; Bathbun, Proc. U. 8. Nat. Mm. ix. (1886) 



p. 267 ; Bell, Ann. Sf Mag. iv. (1889) p. 436. 

 Phormosoma sigsbei, A. Ag. Bull. M. C. Z. viii. (1880) p. 75. 



A species with very large primary tubercles, which are more 

 numerously developed on the oral than the aboral surface ; they 

 have Avell marked areolae, and from what is known as to their spines 

 it is probable that they are rather long and have a stout calcareous 

 cap : these tubercles are both ambulacral and interambulacral in 

 position. There are but few other tubercles on the surface above 

 the ambitus, but below, and especially near the mouth, there are a 

 number of tubercles, which are also developed on the transversely 

 elongated peristomial plates. Organs of Stewart vestigial. 



Colour deep purple below, grey above, with spots and patches of 

 purple. 



Distribution. Both sides of Atlantic, as far south as the Lesser 



