CHAP, iv.] THE CR VISES OF THE ' PORCUPINE: 161 



weight by being lifted out of the water, and sink- 

 ing slowly away back again to our inexpressible 

 anguish ; glossy whisps of Hyalonema spicules ; a 

 bushel of the pretty little mushroom-like Tisiphonia ; 

 a fiery constellation of the scarlet Astropecten tenuis- 

 pinus ; while a whole tangle was ensanguined by the 

 * disjecta membra ' of a splendid Brisinga. 



There was not much in the dredge-bag that was 

 new. Some large Munidce, with their ( spheery eyne ; ' 

 some fine specimens of Kophobelemnon mulleri; an 

 example of the Euryalid, Asteronyx Icveni. nearly 

 the only Scandinavian echinoderm which we had not 

 previously taken ; and an injured specimen of a 

 flexible urchin, which we supposed to be of the same 

 species as that procured the day before, although it 

 differed greatly in colour, being of a uniform pale 

 grey. Upon further examination, however, it proved 

 ,to be the type of a totally different generic group of 

 the same family. 



Phormosoma placenta resembles Galveria in having 



the perisom flexible, the plates overlapping in the 



same way and in ths same directions ; but the plates 



overlap one another only slightly, and they leave no 



membranous spaces between, so that they form a 



continuous shell. The great peculiarity of this form 



s that the upper surface is quite different from the 



ower. Above, the ambulacral and interambulacral 



irea3 are well defined and in ordinary proportion, 



he interambulacral areae being just twice as wide 



is the ambulacral, and the spines are much like 



hose of Calveria, and are arranged nearly in the 



ame manner. At the periphery the shell comes to 



kind of ridge, and alters entirely ; from the edge 



M 



