128 CLARK. 



The smaller ones are found chiefly at the anterior end of the 

 body where they are fairly numerous, about 350 or so per 

 square centimeter in a normally contracted specimen ; near the 

 rear end there are only about tvvent3r-five or so per square centi- 

 meter. The larger ones are found only near the middle and 

 posterior end of the animal ; they occur about 215 or so per 

 square centimeter near the middle but further back are not so 

 numerous, about 125 or so per square centimeter. The smaller 

 anchors (Fig. 3) are about equal in size to the ordinary anchors 

 of inhcErens, measuring about 188 p. long. The arms are short 

 and thick and quite smooth. A few abnormal ones have a 

 third arm projecting in front (Fig. 5). The posterior end is not 

 at all branched but is simple and very finely toothed. The 

 plates accompanying these anchors are somewhat like the ordi- 

 nary plates of inJicBreus. They measure about 166 /-« x 125 // 

 and have seven large, toothed holes, and numerous small 

 smooth holes at the narrower end (Fig. 4). The bow is not 

 arched out of the plane of the plate, and is only present in part, 

 the center being fused with the plate itself as will be seen in the 

 figures. One curious double plate was found, accompanied by 

 twin anchors (Fig. 6). The large anchors (Fig. i) are about 

 three times as long as the small ones, though they vary greatly 

 in size. A few are only about 300 tx in length but the great 

 majority are over 500 fi and many are over 700 fx. The largest 

 one measured was 733 p. long. The posterior end is not at all 

 branched but is finely toothed. The arms are long and slender 

 and each has about eight teeth on the outer side, the points of 

 the teeth turning upward away from the tip of the arm. The 

 plates accompanying these anchors (Fig. 2) vary greatly in size 

 but are always much longer than broad and are usually much 

 shorter than the anchors. Most of them are from 300 fi to 

 400 II in length but many are nearly 500 11. The largest one 

 measured was 510 /^ long by 260 ^« broad. These plates have 

 from ten to thirteen large, toothed holes arranged in three longi- 

 tudinal rows, and numerous small, smooth, holes at the posterior 

 end, which is often nearly square, though generally the corners 

 are rounded. The bow is merged into the plate itself as in the 



