30 PHOEMOSOMA PLACENTA. 



usually of a paler color tending to pinkish brown, with dark claret patches 

 on the actinal side ; these patches often disappear completely, and the test 

 is then of an ashy light-brownish pink, with spines of a lighter color and of a 

 greenish tint. 



The sharp, small secondary spines which cover the test, as has already 

 been noticed by Thomson and Moseley, cause very severe pain to the hands 

 and arms if these urchins are handled carelessly, and nothing can be more 

 disagreeable than the sharp pain which shoots up one's arm on rashly taking 

 hold of these prizes as they are first brought up by the trawl. The after 

 effects resemble those produced by nettles; the disagreeable feeling often 

 does not disappear for twenty-four hours. 



Phormosoma placenta Wtv. Thoms. 



Phormosoma Sigsbei A. Ac. Bull. M. C. Z., VIII., No. 2, p. 7.">, 1880. 



Lesser Antilles, — Lat. 41= -20' 45" X., Long. 65° 47' Id" W. ir.4-1242 fathoms. 



PI. XII., PL XV. Figs. 3-19. 



To the leeward of the Lesser Antilles this species is found between 150 

 and 400 fathoms. On the east coast, in the Atlantic, it has been dredged 

 from 810 to 1242 fathoms. 



I owe to Mr. Murray the opportunity of examining an excellent series 

 of specimens of P. placenta collected by the "Knight-Errant" in the Faroe 

 Channel. The single specimen collected by Thomson in the " Porcupine," and 

 from which his description was made,* was quite imperfect, and I was misled 

 in describing this speck's again under the name of P. Sigsbei from specimens 

 collected by the "Blake" in the Caribbean and off the east coast of the 

 United States ;is far north as Lat, 41° 30' N. This species has also been 

 collected by the U. S. Fish Commission off Martha's Vineyard. 



In the younger stages of this species we find great differences in the 

 thickness of t he test, and the relative size of the abactinal and actinal sys- 

 tems ;is compared with the diameter of the test. AW- find the same sort 

 of differences, so marked in Toxopneustes from different localities, as regards 

 the permanence of the primary tuberculatum and the number of principal 

 vertical rows. The tuherculation of the actinal surface does not differ 

 greatly in specimens of differenl size ; hut in some specimens the tubercu- 

 latum of the abactinal surface may he limited to a couple of principal vertical 



* Trail oi II- 1, of the Royal Society, Vol. CLXIV. Pt. 2, p. 732, Pla LXIL, LXIII. 



