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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 37. 



parallel ridges, and in the lack of markings on the body, with the 

 last three thoracic segments reddish brown in contrast to the yellow 

 color of the rest of the body. 



Ti/pe-specimeti. — Cat. No. 39.507, U.S.N.M. 



IDOTHEOIDEA or VALVIFERA. 

 Family ARCTURID.^. 



Genus ASTACILLA Cordiner. 



ASTACILLA DILATATA, new species. 



Body narrow, elongate, '2^ nnn. wide and JH mm. long. Surface of 

 body thickly tuberculate. 



Head with the front deeply cxcavale, the antero-lateral angles 

 produced and bifid; the lateral margin is also produced in an 



acute triangular process. The eyes are large, 

 round, composite, and situated close to the 

 lateral margin. About the middle of the 

 head on the dorsal surface are two prominent 

 tubercles, one on either side of the median 

 line. The first pair of antenna? have the 

 basal article large and dilated; the second 

 and third are short and slender and sub- 

 equal, each being only half the length of the 

 basal article; the fourth article is about twice 

 as long as the third. The first antennse ex- 

 tend a little beyond the second article of the 

 second pair of antenna^. The first two arti- 

 cles of the second antennae are short, the first 

 being shorter than the second ; the third 

 article is nearly twice as long as the first two 

 taken together; the fourth and fifth are about 

 equal in length and each is twice as long as 

 the third; the flagellum consists of three 

 articles, the first of which is nearly three 

 times as long as the second, and the last is 

 minute, less than half as long as the .second. 

 The second -antennse are as long as the body. 

 The head is coalesced with the first thoracic 

 segment. The antero-lateral angles of the 

 first segment are acutely produced. The first, 

 second, and third segments are about equal in 

 length; close to the posterior margin of the 

 second and third segments are two tubercles, 

 one on either side of the median line, those of the third segment being 

 long and conspicuous. The fourth segment is twice as long as the third 

 and is much broader anteriorly than posteriorly. The antero-lateral 



Fig. 22. — Astacilla dila- 

 TATA. 5g. (Drawn by Miss 

 V. Dandridge. ) 



