chap, iv.] THE CRUISES 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 tenais- 

 pinus ; while a whole tangle was ensanguined by the 

 ' disjecta membra ' of a splendid JBrisinga. 



There was not much in the dredge-bag that was 

 new. Some large Jluniche, with their ' spheery eyne ; ' 

 some fine specimens of Kopliobelemnon inilllerl ; an 

 example of the Euryalid, Asteroiiyx loveni, 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. 



JPkormosoma placenta resembles Calveria in having 

 the perisom flexible, the plates overlapping in the 

 same way and in the 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 

 is that the upper surface is quite different from the 

 lower. Above, the ambulacral and interambulacral 

 areas are well defined and in ordinary proportion, 

 the interambulacral area? being just twice as wide 

 as the ambulacral, and the spines are much like 

 those of Calveria, and are arranged nearly in the 

 same manner. At the periphery the shell comes to 

 a kind of ridge, and alters entirely ; from the edge 



M 



