BULLETIN OF THE UNITED STATES FISH COMMISSION. 
562 
Remarks . — This remarkable animal is one of the rarest of the Woods Hole Echinoderms, and its 
right to a position in this list is based on the reported capture of specimens by codfishermen near 
Nantucket Shoals and at Oral) Ledge. We failed to find it at the latter place, although trustworthy 
fishermen have assured Mr. Edwards and myself that it is common there, “if you get into deep 
enough water.” It is very abundant off Race Point, Provincetown, Mass., in 35 fathoms, where, in 
August, 1902, I brought up 123 tine specimens in a single haul of a small dredge. At that place the 
basket fish breeds during the latter part of August, and these specimens were full of the ripe repro- 
ductive cells. It is called by the fishermen “spider,” and the particular spot where it occurs is known 
locally as the “spider ground.” Almost nothing is known of the habits and absolutely nothing of 
the development of this remarkable ophiuran. Young specimens with the arms only once forked 
have the disk covered with scales, and are said to resemble Ophiqpholis. One of the specimens taken 
at Provincetown had 5 madrepore plates, but dissection showed that there was only 1 stone canal. 
The history of the discovery of the basket fish, and its original description, are very interesting, and 
are given very fully by Lyman (’65). 
ECHI NOIDEA. 
SEA-URCHINS, SAND-DOLLARS, CAKE-URCHINS, SAND-CAKES, ETC 
The echinoids are less represented in the Woods Hole region than any other 
class, for there are only d species known to occur, and of these 1 is extremely rare, and 
1 is found only in deep, cold water. The d are so unlike each other that there is no 
danger of confusing them; but it must be borne in mind that the young are often 
unlike the adults, for not only do the primary spines increase in number with age, 
but the number and arrangement of the poriferous plates also undergoes a marked 
change in many cases. In the cake-urchins (clypeastroids), moreover, there is a 
marked change in the shape of the test, position of the anus, number and appearance 
of lunules, etc., as the animal increases in size. The following terms, used in the 
descriptions, require some explanation: 
Abactinal system = the group of plates forming the apex of the test (or near it) including the genital and 
ocular plates, and in true urchins the anal plates also. 
Ambitus=the line of largest horizontal circumference of the test. 
Buccal plates=a, circle of plates on the peristome around the mouth. 
Branchial incisions = notches in the edge of the peristome, between the ambulacra and the 
interambulacra. 
Corotial j>lates=any vertical series of plates running from the abactinal system to the peristome. 
Genital plates=the five large plates terminating the interambulacra abactinally. 
Imperforate, tubercles =tuberc\es the top of which is not centrally depressed or vertically perforated, 
Lunules— slit-like openings piercing the test from abactinal to actinal surface. 
Miliary spines = the smallest spines of the test, usually on very insignificant tubercles. 
Ocular plates=the five plates terminating the ambulacra abactinally. 
Peristome = the portion of the actinal surface surrounding the mouth, covered with a membrane. 
Petals = the figures formed by the poriferous zones of the ambulacra, of flat or irregular echinoids. 
Poriferous zones = the vertical areas occupied by the pores through which the feet pass. 
Primary spines— the large spines situated on the largest tubercles of the test. 
Secondary .spines = spines intermediate between primaries and miliaries. 
Key to the Echinoids of the Woods Hole region. 
Test nearly hemispherical, with spines of moderate or large size. 
Spines long; color, deep red, purple, or brown to nearly black Arbacia puncttjlata 
Spines short, numerous; color, green or yellowish; spines sometimes reddish or purple-tipped, 
Strong ylocentp.otus drobachiensis 
Test discoidal, flat, with very numerous minute spines. 
Test without lunules Echinarachnius parma 
Test with five lunules. Mellita pentapora 
