CHAP, in.] THE CRUISES OF THE i PORCUPINE.' 121 



SI 









of the adjacent arm, so that the angles between the 

 arms are entirely filled up by a delicate membrane 

 stretched on and supported by spines, and the body 

 hus becomes regularly pentagonal. There is no trace 

 n the ventral surface of the arms of the trans- 

 verse ranges of membranous comb-like plates which 

 re so characteristic in Pteraster. 



By far the most abundant and conspicuous forms 

 among the star-fishes in deep water were the genera 

 Astropecten and AT chaster, and their allies. At one 

 to two hundred fathoms the small form of Astro- 

 pecten irregularis, A. acicularis of NORMAN, literally 

 swarmed in some places, usually in company with 

 the small form of Luidia savignii, M. and T., L. 

 sarsii, D. and K. I feel no doubt that these two 

 forms, A. acicularis and L. sarsii, are mere deep- 

 iwater varieties of the forms which attain so much 

 larger proportions in shallow water. Mr. Edward 

 Waller took charge of Mr. Gwyn Jeffreys' yacht 

 during the summer of 1869, on a dredging cruise off 

 the south coast of Ireland. He worked principally 

 about the 100-fathom line and a little within it, and 

 procured a magnificent series both of Astropecten and 

 Luidia showing a gradual transition through all 

 intermediate stages between the large and the small 

 varieties. 



The cold area gave us Astropecten tenuispinus in 

 great abundance and beauty. The tangles sometimes 

 came up scarlet with them, and associated with this 

 species a handsome new form of a peculiar leaden 

 grey colour, and with paxillse arranged on the 

 dorsal surface of the disk in the form of a rosette, or 

 the petaloid ambulacra of a Clypeaster. Astropecten 



