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BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Radicular dietellae are placed on the proximal portion of the zooecium 

 and above the chitinous joint. A marginal avicularium, spines, and 

 a scutum are present. 



Genotype. — Monartron {Menipea) cyathus Wyville Thompson, 1858. 



The species of the genus are as follows : 



Monartron (Menipea) fuegensis Jullien, 1888. 

 Monartron (Menipea) fuegensis Busk, 1852. 

 Monartron (Tricellaria) aculeata D'Orbigny, 1839. 

 Monartron (Menipea) longispina Yanagi and Okada, 1918. 

 Monartron (Menipea) cyathus Wyville Thompson, 1858. 



Fig. 84. — Genus Monartron, new genus 

 A-E. Monartron cyathus W. Thompson, 1858. A. Specimen, natural size. 

 B. Small portion, magnified; small sessile avicularia are shown on the front 

 of three of the intcrnodes ( = segments), and in the internode of bifu cation a 

 radicle tube is also seen. C. Single internode; in addition to the constant 

 round mark there is in the specimen another similar mark immediately below 

 the anterior sessile avicularium. (A-C, after MacGillivray, 1881.) D. Dorsal 

 surface to show the articulation. (After Waters, 1913.) E. Sketch showing 

 bifurcation. (After Harmer, 1923.) 



The latter species is a little divergent in its zooecial form and in 

 the insertion of a joint but its ovicell is hypers tomial. Harmer, 1923, 

 identified the first three species. This is not the opinion of Waters, 

 1904. Inspection of the published figures does not, moreover, permit 

 this identification. 



Genus HOPLITELLA Levinsen, 1907 



The avicularia appear only on marginal zooecia which have a large 

 avicularium, the inner half of which is immersed; the distal wall has 

 on each side a Ions: narrow continuation running alone: the corre- 



