30 PHOliMOSOMA PLACEXTA. 
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. Ag. Bull. M. C. Z., VIII., No. 2, p. 75, 1880. 
Lesser Autilles, — L,it. 41° 29' 45" N., Long. 65° 47' 10" W. 154-1242 fathoms. 
IT^I ^*iy P^- ^11- P'- ^^- P¥- ^'-i^>- 
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,* Avas quite imperfect, and I was misled 
in describing this species again under the name of P. Sigd)ci from specimens 
collected b}- the " Blake " in the Caribbean and off the east coast of the 
United States as 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 the test, and the relative size of the abactinal and actinal sys- 
tems as compared with the diameter of the test. We find the same sort 
of differences, so marked in Toxopneustes from different localities, as regards 
the permanence of the primary tuberculation and the number of principal 
vertical rows. The tuberculation of the actinal surface does not differ 
greatly in specimens of different size ; but in some specimens the tubercu- 
lation of the abactinal surface may be limited to a couple of principal vertical 
* Transactions of the Royal Society, Vol. CLXIV. Ft. 2, p. 732, Pis. LXIL, LXIIL 
