‘PORCUPINE’ DEEP-SEA DREDGING-EXPEDITIONS. 
741 
only one of its species which we met with, was dredged about 100 miles off the Butt of 
the Lews in 445 fathoms water on the edge of the warm area, with a temperature of 
7 0, 5 C. It came up perfect and living. The spines were moving freely ; and after the 
animal had rolled out of the dredge upon the deck, and assumed what appeared to be 
its normal form and attitude, curious vermicular movements passed through its test. 
When handled the test moved and shrank from the touch, and had much the feel of 
the disk of a Polaster or other large starfish. 
As this specimen was exceptionally good it was reserved nearly intact to show the 
general characters of the group, a small segment of the ventral surface only having been 
removed to allow the description of the structure of the test and pyramid. The dispo- 
sition of the plates and the structure and arrangement of the soft parts will be more 
fully detailed in the description of the next species, for which there were fuller materials. 
Fragments of plates and spines apparently belonging to Calveria hystrix occurred in 
several of the dredgings on the west coasts of Scotland and Ireland. 
2. Calveria fenestrata, sp. nov. (Plate LXIII. figs. 9 & 10 and Plates LXVI. & LXYII.) 
The test is rounded, slightly pentagonal in outline ; in the largest specimen procured 
110 millims. in diameter. It is greatly depressed, being little more than 20 millims. 
in extreme height in the centre, from which the upper surface droops uniformly to the 
edge, which is sharper than in C. liystrix, although it does not form any thing like the 
keel of Phormosoma. The form and general arrangement of the plates is the same on 
the apical and oral surfaces of the test. The structure of the ambulacral and interam- 
bulacral areas is the same as in C. hystrix; the overlapping portion of the plates is, 
however, much larger and wider, and the strap-shaped portion of the plate is much 
narrower, narrowed in some cases almost to a rod, and thus leaving wide membranous 
fenestrse between the plates. The ambulacral areas are nearly equal to the interambu- 
lacral in width, while in C. hystrix they are at least one third narrower, and the plates 
of the perisom generally are lighter and more delicate (Plate LXVII. figs. 1, 2, 3). 
As in C. hystrix the outer surface of each plate bears tubercles of three kinds : — primary 
tubercles with a large smooth areola, a smooth conical mammillary eminence, and a 
perforated mamelon ; smaller tubercles of a similar character ; and miliary granules. 
The arrangement of the primary and larger tubercles is nearly the same as in C. hystrix, 
but they are fewer and more remote. 
The spines are, as in the species previously described, of two kinds. The large spines 
articulated to the primary tubercle are like those of C. hystrix, only they are somewhat 
more delicate ; the ridges on the shaft of the spine are more numerous, and the pro- 
jecting processes are irregular and less strongly marked (Plate LXVII. fig. 4); and the 
collar at the tip of the conical portion of the spine to which the muscle is attached is 
more irregular in outline. The smaller spines are extremely delicate transparent fenes- 
trated tubes. 
The pedicellarise are of three kinds. The largest of these are arranged, both on the 
