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margin, which in the larger specimen is more distinct than in the smaller. The carinal margin 

 bowed and longer than the tergal margin; where these margins meet an obtuse angle is 

 formed and from this angle a not very prominent ridge runs to the occludent margin. This 

 is the only ridge on the outer surface of the scutum. Internally a not very prominent ridge 

 runs alonCT the lower half of the occludent margin, whereas a much more prominent and bowed 

 ridge separates a small basal portion from the rest of the valve. Where these two ridges meet, 

 near the occludent margin, a relatively strong tooth having the shape of a little nail, is formed. 



Tergum (fig. i and 3^) triangular, relatively small. Carinal margin and scutal margin 

 have about the same length ; the former does not show the flattened border which is so 

 characteristic for J/, striatum. 



Carina (fig. 2, 3^ and 4) broad towards its basal end, much bowed, terminating 

 upwards in a narrow flat part which runs up to the basal ends of the terga. The flattened 

 dorsal margin is narrow and has about the same breadth throughout its length. The base is 

 abruptly truncated. The scutal margin at one third of its length from the base shows a small 

 tooth or excrescence which fits into an indistinct excavation in the carinal margin of the scutum. 

 This detail of the structure seems more strongly developed in younger specimens — it cannot 

 at any rate be made out so sharply in full-grown specimens without isolating the valves. 



Peduncle very short, slightly extending from underneath the capitulum. 



Size. The largest specimen has a capitulum of i cm. in length. 



Mouth. La brum (fig. 5) bullate ; crest with a row of numerous (±40) small triangular 

 teeth; Palps small, hairs numerous at the tip and along the interior margin. 



Mandibles (fig. 6) with four teeth, the inferior angle terminating in a single delicate 

 spine. The distance between the tips of the first and second teeth one and a half times as 

 great as that between the tips of the second and third. 



Maxillae (fig. 7) with three spines at the upper angle, the notch beneath the upper 

 spines relatively large and the inferior raised part rather narrow. There are three delicate hairs 

 or spines planted in the notch, and about ten larger ones on the part beneath the notch. 



Outer maxillae of a quadrangular .shape with rounded edges. Numerous, delicate 

 hairs planted on the outer surface, the largest along the outer margin. 



Cirri. First pair far removed from the second pair with very short rami. Rami not so 

 much differing in thickness, much more so in length. The longest ramus has ten, the shortest 

 nine segments. Spines planted over a great part of the surface of each segment. The second 

 cirrus has about the same shape and structure as those following : each ramus consists of long 

 and narrow segments; two stronger and a third much more delicate spine are planted at the 

 conve.x side near the extremity of each segment ; the concave side having as a rule three 

 stronger pairs of .spines and a fourth very delicate pair. An extremely delicate spine is inserted 

 in the angle formed by each pair of stronger spines. 



Caudal appendages (fig. 8). Very short, terminating abruptly and broad, and 

 bearing a not very large number of fairly strong hairs at its truncated extremitj-. 



Penis in the specimen that was dissected broken oft'; the part attached to the body 

 cylindrical with hairs here and there. 



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