142 
R. Rathbun — List of the Brazilian Echinoderms. 
skin is nearly smooth, of a brownish yellow color, and with two 
rows of large purplish brown spots along the dorsal side, and many 
smaller, darker spots scattered promiscuously, but most numerous 
on the lateral and dorsal surfaces. The skin is further covered with 
a net-work of fine reticulations of slight purplish color, giving it a 
tessellated appearance. A narrow line of the same color extends 
through the middle of the interambul acral spaces. 
The ambulacra! zones are of sub-equal width, and about two to 
three times as broad as the intervening spaces. The suckers are 
moderately abundant, slightly more numerous in the median ventral 
than in the other zones, but without regular arrangement, except 
toward the posterior extremity, where there are two rows to each 
zone ; near the middle of the body, about four to five range across 
each zone. Around the anus there are five clusters, each of five to 
eight, more or less pointed papillae. 
The plates of the skin (with suckers) are very numerous, and of sev- 
eral very distinct kinds. The commonest kind is the smallest; minute, 
flattened, regularly oblong-elliptical in outline, with six small, elongate 
perforations, arranged in two rows. Four other kinds are common : 
(1.) A larger, heavier plate, with the margin forming four strong 
lobes, to each of which corresponds a large, circular perforation, 
each lobe in turn being usually divided into two or three smaller 
lobes, bearing a large rounded tubercle ; two or three similar tuber- 
cles occur between the perforations. This plate may be much 
enlarged, the number of perforations increasing in proportion. (2.) 
A table-shaped plate, smaller than the last, and composed of a nar- 
row, upper rim of a squarish outline — a square, with slightly curved 
sides and rounded corners — pierced at each corner by an oval hole, 
or seldom with a complete circle of perforations ; and four legs, which 
begin just within the corner perforations, and bend strongly inward 
for one-half their length, to where they are banded together; below 
this they are straight, and closely joined at the base, leaving only a 
small central perforation, surrounded by ten to twelve pointed, diver- 
gent tubercles. (3.) A slender, flattened, elongated plate, bulging 
strongly outward on both sides at the center, and tapering slightly 
to the ends, which are also enlarged and rounded ; on each side of 
the center there is an elongated perforation, and the rounded ends 
have one to three small holes. This plate is sometimes broadened 
and bears a row of perforations along one-half or all of one side. 
(4.) A rather small cage or basket-shaped plate, of nearly globular 
form, coming probably from the suckers. 
