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MARINE ISOPODA OF NEW ENGLAND, ETC. 375 



The second and third segments are each about half the length of the 

 first. The epimeral sutures are evident, and the epimera are rounded 

 behind in the second segment, but a little more prominent in the third, 

 becoming acute and increasing in size and extension backward to the 

 seventh. The lourth segment is slightly shorter than the third, and i)er. 

 haps a little broader; the last three are short, decreasing in length to 

 the seventh, but maintaining about equal width. The legs are short and 

 rather robust. The first pair have the carpus triangular, but this seg- 

 ment becomes more elongate in the succeeding pairs. The dactyli are 

 robust, and are armed with a strong curved spine or claw at the tip and 

 a smaller one below it. The merus, and usually the ischium and carpus, 

 bear a few spiniform tubercles on the lower surface except in the last 

 pair, which are also more elongated and slender than the others. 



The pleon is scarcely narrower than the thorax, and tapers but little ; 

 the first four segments are of equal length ; the fifth is longer with a 

 median elevation and a transverse depression on each side. The last 

 segment (pi. IX, fig. 57a) is transversely oval or subcircular, broader than 

 long, with the anterior margin raised, especially at the middle, where the 

 elevation is continued a short distance on the segment, but posteriorly 

 it is flattened. The posterior margin is ciliate with hairs of various 

 lengths. The uropods (pi. IX, fig. 57b) are attached just in front of the 

 middle of the segment at its widest part. They consist on each side of 

 a somewhat wedge-shaped basal segment, ciliated and bluntly denticu- 

 lated distally on the outer side, and supporting two rami, between which 

 it is produced below into a strong tooth-like process. The outer ramus 

 is very short and curved outward ; the inner is not as long as the basal seg- 

 ment, and is ciliated externally and at the tip. Underneath, the pleon is 

 much ex(;avated for the pleopods, which are strongly ciliated. The first 

 pair (pi. IX, fig. 57c) consist on each side of a short basal segment bear- 

 ing two lamellae; the inner lamella is almost four times as long as 

 broad, Avith nearly parallel sides, ciliated at and near the tip ; the outer, 

 which is also in front of the inner, is sub-oval with the outer margin 

 more convex than the inner, ciliated near the tip and along most of the 

 outer margin, and inserted a little obliquely upon the basal segment. 

 The next three pah^s of pleopods are similar to the first pair on each 

 side, except that in the males the second pair (pi. IX, fig. 57 d) bears a 

 stylet (s) articulated to the inner margin of the inner lamella about the 

 middle. The posterior pair of pleopods are smaller than the others and 

 not ciliated. 



Length 4.5"""; breadth 1.5™""; color light grayish. 



Much has been written upon the destructive habits of the Idmnoria or 

 " gribble " and the means of preventing its attacks on woodwork, for 

 which the reader may consult especially the publications of Leach, Cold- 

 stream, Hope, Thompson, Moore, Gould, Bate and Westwood, Verrill, and 

 Andrews, who has observed it attacking the gutta-percha of submarine 

 telegraph cables. 



